Mirai is Kako's little sister. Before the incident that revealed her brother's cross-dressing interest, she used to get along very well with him. When she found out about it however, she was grossed out and refused to accept him, calling him "disgusting". After being convinced by him, she agreed to his cross-dressing and even lent him her clothes, but with two conditions: one, he must pay a rental fee; and two, he must not come near her while cross-dressed - though the latter was broken more than once. Mirai is shown to be unorganized, even leaving her clothes lying around - which in turn caused Kako to discover his interest in cross-dressing. Her name is probably a pun on "mirai" which means "future" in Japanese.