Black Seppuku Rabbit is the messenger assigned to the Kämpfer Akane Mishima. This creature is sent by the Moderators, the unseen entities who oversee the Kämpfer battles. As is typical for these messenger animals, Black Seppuku Rabbit is depicted with its internal organs visibly protruding from its body and has blood around its mouth.

In terms of its role, Black Seppuku Rabbit serves as a companion and an informant for Akane. It is one of several similar creatures, each attached to a different Kämpfer. The primary relationship for this character is with Akane Mishima, to whom it is bound as her messenger. The character’s background, personality, motivations, development throughout the story, and any notable abilities beyond its basic function as a messenger are not documented in the available information.