Bronya Zaychik's mecha partner in arms utilized for combat. It has the ability to fire cannon shots, concentrated lasers, or cluster missiles. In Honkai Impact 3rd, it takes on a slightly different look depending on which battlesuit Bronya is using. With Wolf's Dawn Valkyrie form Project Bunny is able to act independently apart from her as its own unit on the field. After Bronya becomes Herrscher of Reason, it becomes able to turn into a motorcycle.
Later down the story in Honkai Impact 3rd, such as in Chapter 36, Project Bunny is given to Seele Vollerei (post #6181303), and even becomes an obtainable ELF as of version 6.8. This ELF version is voiced by Risa Tsumugi in Japanese.
