Yamimaru

Tōya's servant bat who is the only one that Tōya can rely on, especially if Tōya has collapsed from a lack of energy. He has the ability to transform into a normal looking human, though this can only be done for about 4 and a half hours per day. He has two human forms: one that is very tall (6'6") and theoretically looks like Tōya's older brother, and a much younger version who can theoretically appear to be Tōya's younger brother.