Reiko (レイコ) is a major character in the OneeChanbara series, serving as an antagonist and sometimes as a playable character.
She is re-imagined as Lei (レイ Rei), pronounced in-game in English audio as Rei, in OneeChanbara ORIGIN. Lei's Japanese voice is provided by Yū Kobayashi while her English voice is provided by Brianna Knickerbocker.
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 reaction 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.
It is suggested that all Reiko clones defeated before the events of Bikini Zombie Slayers belong to the mass-production model: when Saki suspects the opponent of using sheer numbers again upon encountering a Single Digit clone during the events of Bikini Zombie Slayers, the clone reminds Saki not to confuse her for the mass-production cheap thrills; after defeating the clone, Saki remarks that for the first time ever she felt evidences of humanity from the clone.
The Wii console installment also has an unlockable story arc featuring Reiko №9, one of the Single Digit clones, as the protagonist. It paints both the original Reiko and her clones in a more positive light, stating that despite extreme methods that have put her clones in conflict with Aya and Saki, Reiko's true aim is not only to wipe out the undeads but also to prevent the Baneful Blood descendants from turning against the living afterward. As she sets about capturing identified carriers of the Baneful Blood, however, the clone is able to observe genuine love between Aya and Saki as well as their hope for the future, prompting the collective consciousness of the original Reiko as well as the surviving Single Digit clones to re-evaluate their methods with the hope that Baneful Blood descendants might yet be able to co-exist with the rest of Humanity after all. Reiko №9 possesses an alt-attack mode that grants her the use of firearms and comes equipped with a semi-automatic shotgun and a submachine gun. She becomes available upon completing Aya's story arc.
[Rough Translation] A fellow hunter of undead spirits, she contacted Aya and offered her service as an information dealer.
In return for Aya exterminating the undead at her behest, she passes along any clue that comes her way as to the possible whereabouts of Aya's family and is therefore treated as a full partner by Aya. Such exchange of information is carried out by means of long-range communications.
Most aspects of her remain mysteries.
However, she appears to have sisters of her own.
