- Main article: Aya
The main central protagonist in Onechanbara series. Raised by her now-deceased father and trained in sword arts, Aya has done her best to have a normal life with her half-sister Saki yet been sometimes feeling a little bit insecure about her family's "Baneful Blood" curse, which has a tendency of sending her into berserk state. Her alternate attack mode has her wielding two swords at once, which furthers the potency of her standard sword-fighting techniques. She is voiced by Yûko Kaida in Bikini Samurai Squad.
- Main article: Saki
Saki is Aya's younger half-sister and descended from the same cursed bloodline, Saki is said to be even more vulnerable to its berserk rampage reaction, suggesting that her mother might also be part of the bloodline while Aya's mother might not. In pursue of swordsmanship, however, their father eventually left Saki and her mother to fend for themselves, a fact that she was resentful of and ultimately drove her to assassinate him after watching her mother dying in illness and poverty. Later she discovered an ancient artifact that allows her to reverse her mother's death... but requires her half-sister as a sacrifice. This leads to the story of the first OneChanbara game, which ends with a climatic battle and her defeat at Aya's hands. Aya, however, chooses to spare her life and take her to medical assistance in the end.
The second OneChanbara begins soon afterward, with her disappearing during transit from one hospital to another. Saki is later found under attack by a Reiko clone, who has identified her as the one responsible for a new zombie outbreak then taking place, and rescued by Aya. Aya is able to locate the real source of the crisis, however, and bring the situation to a conclusion where Saki remains safe. She is voiced by Nao Takamori in Bikini Samurai Squad.
- Main article: Annna
A special force soldier from the Zombie Prevention Force (Z.P.F), she meets and allies with the two sisters early in the game, first by bailing Saki out of captivity from Himiko's aides. Her military background gives her access to firearms, explosives, and some (although not quite as sophisticated as Saki's) melee combat techniques. Later in the game it is revealed that Anna's brother David has been kidnapped and brainwashed by the game's antagonist Himiko. She is voiced by Kazusa Amagai in Bikini Samurai Squad. As a mistake, the game writes Anna's name with three n's istead of 2. It's spelled with only two n's.
- Main article: Kagura
- Main article: Saaya
- Main article: Misery
Part of Himiko experiment involving Imichi Blood that gives her powers smillar to Aya's and Saki's. In Bikini Samurai Squad Misery is a boss in several stages. Being revived by power left behind by Himiko, this yet another descendant of the "Baneful Blood" is now only interested in exacting revenge upon Aya and Saki. Aside from her blood, her sword is very huge. In Onechanbara: Bikini Zombie Slayers, Misery can change her sword's shape just like Eva (from Zombie Hunters 2).
- Main article: Himiko
Around 200-300 years old woman and antagonist in Bikini Samurai Squad. She is killed by Annna, Aya and Saki at the end of the game. Himiko is voiced by Kahoko Yaki in game. She is a playable DLC character in Bikini Samurai Squad. Just like Eva she appears in only one game and is mentioned in sequels. She reappears as a final boss in OneChanbara Special.
- Main article: Eva
Secondary antagonist in Zombie Hunters 2. Beautiful green-haired woman with whip sword as weapon. At the end of the game she is killed by Aya, Saki and Reiko. Reiko later ate Eva's heart. She is often mentioned by Aya and Reiko in Bikini Samurai Squad, but she is not shown in this game. Her weapon is similar to Misery's in Bikini Samurai Squad.
- Main article: Reiko
The tritagonist turned main antagonist in Zombie Hunters 2. Reiko as encountered by Aya and her party from time to time is in fact no single-person but clones of a scientist that is working to unlock the secret behind the zombie outbreak since its beginning. The clones at first were created for the original Reiko to experiment on with the Baneful Blood and presumably meant to be expendable. This has apparently changed later when, in order to more-efficiently carry out her will, the original Reiko wired herself into a computer network and began developing more-sophisticated clones to serve as her eyes and ears in the field.
These new generation of clones, benefiting from progress made on humanity's understanding of the Baneful Blood descendants (for example, excessive exposure to the Baneful Blood triggers "berserk" state on them instead of outright killing them), are divided into two categories: the "Single Digits" model, the nine clones based on the original Reiko, and the mass-production model, simplified versions of the "Single Digits" model. All clones have been genetically enhanced for their specific functions, but only the "Single Digits" model is capable of the full-range of investigative tasks from intelligence gathering to self-defense combat. Also, all nine Single Digits clones are telepathically linked to one another and the original Reiko. She is voiced by Yuki Hishijima in Bikini Samurai Squad. Reiko first appeared in the Onechanbara 2 as a mystery character, wearing a motorcyclist's suit and helmet, which obstructed her face from outside view.
- Main article: Carmilla
- Main article: Evange
- Main article: Riho
Makoto's older sister, quest character in Zombie Hunters and Zombie Hunters 2. She is 17 years old during the events of Zombie Hunters. Her main costume is a blue bikini. Riho also appeared in dozen other D3Publisher games including Dream C Club or its sequel Dream Club Zero.
- Main article: Makoto
Riho's younger sister, quest character in Zombie Hunters and Zombie Hunters 2. Sadly, she only appears in the first oneechanbara games. She is 15 years old during the events of Zombie Hunters. In an attempt to follow in the footsteps of her older sister. Makoto has just finished filming her first movie, the slasher horror genre, a true professional, especially in the final scene, where she is facing a bloody fight with her sister.
- Main article: Kiku
Cyber defense soldier and Hana's older sister. A quest character in Zombie Hunters 2. Kiku and Hana received their own game on PS2 in 2004. The game is called 'Dragon Sisters', like most of Simply 2000 Series it was released in Japan and Europe. Her weapon is a sword.
- Main article: Hana
Cyber defense soldier and Kiku's younger sister. A quest character in Zombie Hunters 2. Kiku and Hana received their own game on PS2 in 2004. The game is called 'Dragon Sisters', like most of Simply 2000 Series it was released in Japan and Europe. Her weapon is a sword.