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Chapter 01: Resurrection of the Dead[]
In a cemetery somewhere in Tokyo, Aya stands before her stepmother's grave, intent on figuring out the meaning behind an e-mail message she received from Saki. The message: "Die won't you, for Mom's sake?" Before the ominous tone of the message can fully sink in, she is ambushed by zombies, but the ambush proves fruitless against Aya, a master swordsman and Undead hunter. After clearing the area of Undead, Aya is contacted by her informant Lei, who she tells that her stepmother's coffin is missing from the grave. As Lei wonders about that, Aya makes the dark joke that Saki might be looking to resurrect her mother. Lei then gives Aya the tip that a girl in a sailor uniform was spotted in a hospital nearby. Believing the girl to be Saki, Aya heads to the cemetery's exit.
Along the way, while Aya battles zombies blocking off her exit, Lei speaks to Aya about the text message. Aya reveals to Lei that the sisters have a distant relationship akin to strangers due to the two of them having different mothers. Lei reveals for herself that she has sisters too, but she views them as a nuisance. This leads Aya to end the conversation by stating that Saki is likely a strong lead to finding her father.
Chapter 02: Corpse Vanquisher[]
Before Aya can fully leave the cemetery, she is ambushed by Devda, a gigantic Undead man that can swing its giant sword with massive force. During the course of the battle, Aya enters Berserk Form, a condition inherent in members of the Baneful Bloodline that causes their skin to darken, hair to become a pale color, and a blood-red aura to emanate from their body. More importantly, it grants Banefuls a considerable increase in strength. Banefuls who enter Berserk Form also assume a more sadistic personality. Eventually, Aya kills Devda by slicing him in half. Afterwards, Lei informs Aya about a shopping app she can use to purchase consumable goods. Aya continues her trek to the abandoned hospital.
Chapter 03: Abandoned Hospital[]
At the hospital, Lei asks Aya why she became an Undead hunter. Aya initially explains that it lets her use the sword skills taught to her by her father before concluding that the choices and actions she commits to are for her own sake. Lei expresses understanding, stating that their zombie-hunting work is quite normal in the world they were born into.
Chapter 04: Uroboros[]
Aya reaches an x-ray room and notes the peculiarities in the room. Lei reveals that the hospital had been formerly run by the organization Uroboros, who had been performing unethical research. An accident caused the hospital to be shut down. Although intrigued by Lei's information, Aya continues her search for the girl in the sailor uniform by using the room's elevator.
Chapter 05: High School Corpse Girl[]
Upon the elevator doors opening to an operating room, Aya finds the girl in the sailor uniform and assumes it is Saki. However, the girl in question is revealed to be Anzu, an Undead girl with the unusual ability to speak. She explains that she was given the order to kill Aya. Giddy that she'll be able to surprise her "Sissy" with good news, Anzu does battle with Aya. As the two girls battle each other, Aya expresses disappointment at the girl not being Saki before wondering if Anzu was an experiment of Uroboros, while Lei expresses more interest in the "Sissy" person she mentioned, potentially suggesting that it could be Saki. Although quick and nimble, Anzu proves to be no match for Aya. Before Aya can register the killing blow, a short earthquake occurs, distracting her and allowing Anzu to escape.
Chapter 06: Big Sister's Heart[]
As Aya leaves the room, Lei wonders if she let Anzu go on purpose because she reminded her of her little sister. Aya shrugs it off and continues her pursuit of Anzu. She then wonders where the girl went, to which Lei suggests she check the roof. Remembering Anzu's "order" to kill her, Aya wonders who could be controlling the girl and if they might also be behind the frequent zombies she's been encountering lately. Lei jokes that the person possibly responsible sounds like a "final boss." Once at the door to the roof, Aya senses a presence unlike an Undead's. Lei believes it might be Aya's little sister beyond the door.
Chapter 07: Anzu and Sayaka[]
Unfortunately, the presence Aya felt came from Anzu's older sister, Sayaka, another Undead girl. Believing it her duty as an older sister to protect her younger sister as well as also given the order to kill Aya, Sayaka, alongside Anzu, does battle with Aya. Although Aya expresses disappointment at the second schoolgirl zombie she finds not turning out to be Saki, she then asks Lei if she knows about an "Eva" person that Anzu let slip as their mistress before the battle. Lei responds that she doesn't know anyone by that name, but she will look into any information she can find.
Although the iron claw-wielding Anzu and the powerful, giant flail-wielding Sayaka make up a deadly combination, Aya is able to tangle with them and defeats Anzu first. Worried for her sister's safety, Sayaka throws Anzu over the roofside and yells at her to survive. She then repeats to a puzzled Aya her self-proclaimed duty as an older sister to protect her younger sister before entering Berserk Form, revealing that she is another member of the Baneful Bloodline. Although Sayaka possesses inhuman strength, heightened further through Berserk Form, she is ultimately defeated and fatally wounded by Aya. With her last breath, Sayaka expresses gratitude to her mistress Eva for reviving her, allowing her to reunite, even for a brief time, with her younger sister. She feels that she fulfilled her duty to protect Anzu before finally passing away. Moved by the Undead girl's dedication to her sister, Aya clasps her hands together as if praying. After Aya rearranges Sayaka's body as if to be placed in a coffin, Lei tells her to leave it behind so she can pick it up. Aya assumes that Lei is going to bury her and feels grateful to her for it.
Chapter 08: Father of Confusion[]
As Aya reenters the hospital and renews her pursuit of Anzu, Lei wonders if she was moved by the words of "that Sissy creature," to which Aya denies it. Afterwards, Aya takes the elevator in an attempt to reach the first floor and search for Anzu. However, the elevator erroneously takes her to the basement, leading Lei to assume that Aya is bad with machines. From the elevator, Aya notices corpses of women with white hair and strange, black attire. Upon hearing this, Lei laughs, puzzling Aya as she vaguely considers the grim scene a screwup she wished she could have seen. In the same room, Aya takes note of a diagonal opening in a door that looks to have been caused by a clean but powerful slash of a sword. Taking great interest as if she knows what caused it, Aya enters through the hole to reach the end of the hallway, passing by more female corpses strewn along the way.
Upon entering the room at the end of the hallway, Aya notices a man in the center of the room and recognizes him as her long-lost father Oboro. Before Aya can ask him any questions however, he notices her and mistakes her for his wife Tsubaki's murderer, preparing to kill her by tapping into his Baneful blood to enter Berserk Form. Although perplexed at the strange turn of events, Aya is forced to fight her father. During the course of their battle, after sustaining much physical and mental trauma, Aya feels her body become hot and enters a new transformation: Xtasy, a Baneful transformation that causes the user to assume a demonic appearance and heightens their strength well beyond Berserk Form. However, Banefuls undergoing this powerful transformation run the risk of going completely insane, lost in the ecstasy they derive from violence and bloodshed. Before this can happen to Aya however, Oboro, while fighting through his insanity, temporarily comes to his senses to apologize to his daughters for keeping them apart. Aya, realizing that she almost lost her mind, resolves to stop her father.
Eventually, she is able to knock his senses back into him, allowing him to explain himself about his two-year disappearance. He reveals that, while keeping his berserk Baneful blood at bay, he had been chasing after Tsubaki's murderer and that it was a woman named Eva, another member of the Baneful Bloodline, that killed her. He also reveals that she brainwashed Saki into believing that she can resurrect her mother with a Baneful's heart, causing Saki to desire to fight the two of them. Although Oboro asks Aya to stop Saki, Aya tries to explain that it's difficult to stop someone trying to kill her without killing them herself. This leaves Oboro no choice but to reveal that Aya and Saki are not half-sisters, but are indeed real sisters. Oboro and Tsubaki kept this truth from their daughters in order to protect them from a Baneful tradition that forces full sisters to fight to the death. Although incredulous at the sudden truths thrust upon her, Aya agrees to stop Saki, knowing full well of her father's vendetta.
Chapter 09: Searching for Family[]
Before Aya begins her path towards Saki, Oboro gifts her two katanas, knowing that she'll make the most out of them. Aya then returns to the room with the elevator to enter a broken wall closed off by caution tape. She eventually makes her way to an underground sewers. As Aya makes her way through the sewers, Lei expresses concern for her safety considering her burden to stop Saki and Saki's own desire to kill her. Aya assures Lei that, because Saki is her little sister who had just lost her mother, she will stop Saki without killing her. However, Lei believes this goes against Aya's previous statement that she chooses to do things for her own sake.
Deep into the sewers, Aya encounters the giant Undead infant Ubie sleeping on a plateau in the center of a large room. A large door is blocked off by pink gunk seemingly of the same material as what surrounds the base of the plateau. Unable to enter the door, Aya, after wondering if the sleeping creature was another failed experiment of Uroboros, sneaks around it to look for another way deeper in the sewers. Along the way, Lei makes small talk about Aya's father, to which Aya explains that she knows him well enough that he won't budge when he's strongly intent on doing something. This conversation leads Aya to ask about Lei's own father, but Lei responds that she is unable to answer her question before showing annoyance at Aya's line of questioning. Aya then concludes that even Lei has things that she keeps to herself.
Chapter 10: Fate of Blood[]
As Aya continues her trek in the sewers, Lei starts to make strangely dark commentary about Aya's inevitable battle with Saki, expressing an unusual amount of enthusiasm for their "fight to the death." Confused by Lei's comments, Aya asks Lei if she is able to kill any of her own sisters, but Lei tells her not to mind about her. Eventually, Aya reaches a dead end in the sewers that leads into an Undead ambush. While Aya takes care of the zombies, Lei makes the conviction that there's no way for the both of them to survive, ultimately stating that competition is the cruel destiny of sisters. Although Aya is perplexed and unnerved by Lei's declarations, Lei simply tells her to watch herself.
After clearing the room of Undead, another brief earthquake occurs, indicating that Ubie has woken up and become agitated. Aya realizes that she must fight the creature to advance on her path.
Chapter 11: Birth Cry from Hell[]
When she makes her way to Ubie, Lei expresses disgust for the creature and informs Aya that she must sever the umbilical cords rooted into the ground, its sources of nourishment, in order to kill it. With this info, Aya is able to seemingly kill Ubie, allowing the pink gunk blocking the large door to disappear. Aya is finally about to reach her sister Saki.
In an abstract mindspace at an unknown time and date, Saki, after lamenting her mother's death, is met by the mysterious woman Eva. Taking advantage of Oboro and Tsubaki's lie, Eva brainwashes Saki into believing that her father killed her mother and abandoned Saki because he cherished her half-sister Aya more. She then informs her of a way to resurrect her mother, allowing Eva to place a curse on her.
Chapter 12: Beyond the Death Battle[]
After entering the large door, Aya reaches an underground cavern housing a peculiar temple. Right outside the temple, she encounters Saki, who expresses her desire to kill Aya in order to obtain her heart and resurrect her mother. The two Baneful sisters Aya, who seeks to convince Saki of their full-blooded relationship, and Saki, who is falsely convinced that Aya is the child of their father's previous lover, cannot but begin their battle to the death.
Over the course of a grueling battle, Saki sustains enough physical and mental trauma to enter her own Xtatic Form. Afraid that Saki will lose herself to bloodshed-derived ecstasy, Aya assumes her own Xtatic Form to match Saki's power, declaring that she will end the Baneful tradition of mortal combat between sisters. The battle ends in a clash between Aya and Saki's swords, with Aya the victor as she disarms Saki. Reverting from her Xtatic Form, Saki awaits her death at Aya's blade. To her surprise, she is brought into Aya's loving embrace and smells her mother's scent on Aya. Aya explains that they are real sisters, having witnessed Saki's birth and promising to protect her before being told the lie that Tsubaki isn't her real mother, ultimately leading to the split in their family. Aya then promises that she won't abandon Saki ever again, to which Saki bawls, finally lifting Eva's curse.
Some time afterwards, Aya and Saki return to the cemetery to rebury their mother. After apologizing to their mother, Saki asks Aya what they're gonna do next. Aya explains that they must search for their father, who is fighting to avenge Tsubaki's death. Upon hearing this, Saki resolves to fight alongside her sister, and so the two head off to look for their father.
Chapter 13: Sisters[]
A few days have passed since the sisters' fateful death battle, with no sign of their father. Searching for him in the abandoned Asakusa district of Tokyo, Aya travels with her sister as she wonders what happened to Lei, having lost contact with her since the death battle. Along the way, Aya and Saki engage in sisterly bonding via lighthearted conversations while coming across a huge hole in the ground, wondering what could have come out of it. After traveling for some time, the sisters take a break. Upon being asked about Lei, Aya explains that she had previously been aiding her by providing information as to the whereabouts of Oboro and Saki. However, she never met her in person, so she wouldn't recognize her if she saw her. Saki becomes both worried and suspicious. The sisters then continue their search.
Chapter 14: That Informant[]
The sisters finally catch a glimpse of their father from a distance and attempt to catch up with him. However, a mysterious woman suddenly appears and interrupts their pursuit. She points a gun at Saki and fires, but Aya deflects it in the nick of time while declaring that it is her duty as an older sister to protect her younger sister. The sisters do battle with the mystery woman. Afterwards, the woman stops the battle and reveals herself to be Lei. Although Aya is surprised, Lei explains that she instigated the battle in order to gauge Aya's fighting ability and confirm that it really is her. She then offers to aid them in the search for their father. Saki angrily replies that it was her fault that they just lost their father.
Chapter 15: Footprints[]
Claiming that she has an idea where Aya and Saki's father went, Lei leads them to the abandoned commercial pathway to Sensoji temple. Along the way, Lei and Saki become familiar with each other, despite Saki considering Lei's presence an annoyance that cuts into her time spent alone with Aya. Aya also asks Lei where she had been since they lost contact, but Lei gives vague answers, increasing Saki's suspicions. Right before the main gate to the temple, Saki alerts Aya to a teddy bear, leading Lei to express disgust while Aya expresses adoration. This leads to some slight teasing from Saki and Lei about Aya's interesting tastes. The girls also come across an unusually large footprint. Lei recognizes its owner and expresses both disgust and dissatisfaction at Aya not having killed Ubie.
Chapter 16: That Nightmare Again[]
At the base of the dilapidated temple, the three encounter Ubie and do battle with it, eventually killing it once and for all. While Aya and Saki wonder about its immense size for an Undead infant, Lei exhales with a disappointed look. They then continue their path to the Asakusa Mall. Along the way, Aya shows interest in a poster presenting "Drowsy the Bear," a famous circus bear. Lei explains that the mall zoo was likely destroyed ages ago while Saki gets goosebumps at the thought of an Undead bear. At the entrance to the mall, Aya recognizes a diagonal hole in the door to be the work of their father. The three head inside.
Chapter 17: Circus of the Corpse Beast[]
Once inside, Aya and Saki catch their father from a distance again but fail to meet up with him as he enters a door seemingly made out of flesh before he and the door disappear out of thin air. Saki recognizes the door as a creation of Eva's powers, leading Lei to remind her that she used to be Eva's minion. Aya of course tells Lei to cut it out. While making their way around the mall to look for another way to their father, the girls recognize the closed shutters as indication of the mall having been previously used as a shelter. Afterwards, Saki, feeling a lot closer to Aya, reveals to her that their mother was formerly a master of martial arts before being forced to retire from a leg injury.
At the center of the mall, the girls are ambushed by an Undead bear. Recognizing the bear as the circus performer seen on the poster, the girls do battle with it. The Undead bear gives Saki enough trouble that it forces her to invoke her mother's name and engage the Tsubaki school "Mortal Combat" fighting style. Eventually, they kill the bear. While Aya shows admiration for the gift their mother imparted to Saki, Lei watches them from a distance as she listens to a voice that informs her of a mission to kill the sisters before they are able to meet with Oboro. Lei curses the voice, hoping that "they" don't give her trouble.
Chapter 18: Relying on Kindness[]
After the girls enter and clear the food court of zombies, Lei attempts to guilt-trip Saki by positing that Saki follows her sister as if nothing happened, despite originally being Eva's minion. Saki recognizes this fact and her over-reliance on Aya's kindness. After going through the mall's storage rooms, Lei spots an elevator and runs to it, while Aya notices something troubling Saki. Saki shrugs it off, causing Aya to worry.
Chapter 19: Form of a Family[]
Upon leaving the elevator, Aya asks Lei how she deals with troubled sisters. Lei however replies with the useless answer that she either ignores them or hits them. Afterwards, Aya stops an absentminded Saki in her tracks before she is mauled by zombie dogs, leading her to question whether Saki has a death wish. Saki is forced to admit that she is troubled by Aya's kindness towards her despite Saki having previously tried to kill her. Aya explains with the simple answer that Saki is her one and only sister, revealing how much she cherishes family given the fact that every person only lives once. Saki fully understands and accepts Aya's answer while Lei expresses confusion and disgust at their familial and sisterly love.
At the end of the mall, the girls reach an elevator. While Aya heads to the elevator first, Saki catches Lei's attention to tell her that she intends to stay by Aya's side and that she still distrusts her. Lei however replies that she doesn't mind Saki's suspicions, annoying Saki further. When Saki and Lei reach the elevator, Lei brings back the joke that Aya is bad with machines, leading Saki to question Aya about it. Aya of course becomes annoyed by their teasing. When the elevator door closes, six women that resemble Lei reach the area, discussing Number 137 (Lei)'s inability to kill the sisters. Determining that 137 has abandoned her duties, the women commence the termination of 137.
Chapter 20: Responsibility[]
Upon reaching the basement from the elevator, the girls encounter Anzu, armed with both her iron claws and Sayaka's giant flail. She desires revenge on Aya and wishes to use her heart to resurrect Sayaka. Saki, having been in a similar situation to her a few days ago, determines that it is best that she fight Anzu alone. Although Saki claims to understand Anzu's pain, Anzu points out the fact that Saki still has her sister. Saki then declares that she will be Anzu's opponent, angering Anzu and causing her to enter Berserk Form while Saki enters Xtatic Form. The little sisters do battle, ending with Saki fatally wounding Anzu.
When a reeling Anzu looks at Sayaka's flail, she believes that her older sister has been with her the whole time before peacefully passing away. Saki hopes for Anzu to be reunited with her sister in the afterlife and clasps her hands together. When Lei show confusion towards Saki's behavior, Aya explains that it is a custom for their family to take responsibility for their actions. As Lei shows a hint of sadness from hearing Aya's answer, a flesh-like door appears nearby. Aya takes notice of it, feeling that it is calling to them to enter. However, Lei tells Aya that she has something important to do and that she will follow them when she's done. After seeing Aya and Saki off, Lei breathes a sigh of relief before walking over to Anzu's body, which had been rearranged by Saki as if to be placed in a coffin. As Lei determines that Anzu's body could still be of use to Aya, one of the Lei look-alikes appears. Knowing full well the reason behind the look-alike's presence, Lei expresses disappointment and anger.
Chapter 21: The Third Path[]
In a sewers-like area filled with water the color of blood, Eva voices disappointment at Anzu's failure before acknowledging Oboro's presence. Although she believes Oboro cannot defeat her, Oboro claims she is weak no matter how many Baneful hearts she devours. Eva laughs arrogantly, stating that she is the same as him, willing to protect what is precious to her. She then mocks Oboro, asking what he thought of his daughters' death battle before threatening to reunite him with Tsubaki. In another area of the blood-red sewers, Aya senses that their father is in danger.
Deep into Eva's hideout, Saki tells Aya about her wish to apologize to their father for what she's done. Aya however assures Saki that it is only Eva he can't forgive, for she is the one who tore their family apart. She also explains that their father has been fighting nonstop in his Berserk Form ever since their mother's death, continuously losing his sanity and having not much longer to live.
Soon after, Lei contacts Aya to reveal to her that she was moved by Aya's success in carrying out her determination to reach a third outcome in the fated death battle between the sisters. She adds that she will do the same and find her own third path before ending their call and leaving behind her a corpse-laden trail of Lei look-alikes.
Chapter 22: Duplicated Soldiers[]
Although the call perplexes Aya and even Saki, the sisters continue their trek through Eva's hideout. After reaching a dead end and clearing the subsequent Undead ambush, Aya and Saki are attacked by numerous women who look like Lei. The Lei look-alikes affirm their mission to retrieve Aya and Saki's bodies to further Uroboros's research into the Baneful Blood. As Aya and Saki are puzzled by the women's words, Lei contacts them to reveal that they, including herself, are clones mass-produced as experiment and combat test fodder. After cursing the organization's cruel treatment of her and her fellow clones, Lei declares that she will change her destiny, having decided that there only needs to be one of her before ending the call and leaving Aya to wonder what she's thinking. After killing the Lei clones, Aya senses a disturbingly powerful presence nearby.
Chapter 23: Where Xtasy Leads[]
Retracing their steps, the sisters return to a previously traversed wide open area to find their father, who has reached his limit stemming his Berserk Baneful Blood. The sisters are too late, having become witnesses to Oboro's Xtatic transformation: a form resembling a demonic samurai. Having lost their father to Xtasy, Aya and Saki have no choice but to kill him. After becoming fatally wounded, Oboro reverts from his Xtatic Form. Proud that both his daughters have grown up strong, Oboro instills in Aya and Saki the duty to stop those who wish to use Baneful Blood for evil purposes, and to fight for those who are unable to defend themselves before disappearing into numerous, red spheres of light. As Aya and Saki mourn their father's death, the large door before them becomes free from red gunk. The sisters resolve to finish what their father started.
Chapter 24: The Power of a Lie[]
Beyond the large door, the sisters reach a circular arena surrounded by water, all located within a valley. At the center of the arena is Eva. Knowing that the sisters' presence is proof of Oboro's passing, Eva explains that it is the fate of Baneful men to go Berserk before questioning Saki's presence by Aya's side as if nothing happened. When Eva mocks her for believing her lies, Saki declares that she will kill her. Eva smiles, amused, before laughing haughtily and then declaring that she must devour their hearts. Aya returns Eva's declaration by declaring for herself that they will kill her to avenge their parents. The decisive battle between the Baneful sisters and Eva begins with Eva mocking their parents' deaths, while Aya holds steadfast resolve to their duty to fight for those unable to defend themselves. Although Eva powers herself up in Berserk Form, she is ultimately disarmed by the sisters, signaling her defeat.
Chapter 25: ORIGIN[]
Before Eva is able to do anything else, she is caught by surprise by the sudden appearance of Lei and is held up by her neck. Lei then plunges her hand into her chest to retrieve her heart. Afterwards, she throws Eva beyond the bounds of the arena, firing a bullet into her forehead before she plunges into the water, seemingly killing her. With Eva's bloody heart in hand, Lei reveals to Aya and Saki that she had just killed all her fellow clones and destroyed Uroboros. Laughing maniacally, she declares that she has at last become the "ORIGIN." However, Lei does not yet feel satisfied, harboring the ultimate desire to become someone like Aya. Once she retracts her statement and re-declares that she desires to become Aya herself, she devours Eva's heart to gain Baneful power for herself. Despite her wishes, Lei lets out sad whimpers before fully becoming an inheritor of the Baneful Blood, losing her sanity in the process. Aya, recalling her father's words, resolves to take away Lei's suffering. Aya and Saki prepare for the final battle. Despite Lei's newfound powers, the sisters fatally wound her. While being held in Aya's arms, Lei expresses her desire to become Aya once again. Aya, however, tells her that she is herself. With a satisfied, peaceful look on her face, Lei passes away, disappearing into numerous, red spheres of light. Although saddened by her friend's passing, Aya looks up to the sky.
At the cemetery once again, after placing Oboro's sword by Tsubaki's grave, Aya and Saki pray to their parents before walking off. Aya, the heiress of her father's swords, recognizes that her life has changed greatly: she now has a precious sister that she'll always fight for. Saki, the heiress of her mother's fighting style, loves her sister dearly. She recognizes that her sister will always believe in her and wishes to never lose a loved one ever again. With their unwavering resolve to use their Baneful power to fight for those who can't protect themselves, the sisters promise their parents that they will fight on.