At some point in the distant past, Tsukuyomi betrayed a friend of hers and the result of which is an unusual scar on her chest, serving as a constant reminder for her actions. Later, Tsukuyomi and another friend encountered Paradox. Tsukuyomi bore witness to her friend challenge Hilda, but he was easily defeated by her overwhelming power.

Currently, Tsukuyomi is allied with Byakuya to fulfill a "wish" of hers. They have participated in the Hollow Night multiple times in an attempt to locate the friend that Tsukuyomi betrayed in the past so that she may make amends, although they have yet to find her.