Kirei features in Operation 04. This young woman possesses pink hair and brown eyes and is characterized as clumsy. She vacations on a tropical island with her friend, Rui. During their stay, both notice peculiarities in the island's native population and the local butterflies' behavior. Their initial experiences include consensual sexual encounters with each other and with the islanders.

The situation shifts when the native, Dabide, invites them to his residence. That night, Kirei awakens restrained while Rui applies a potent aphrodisiac to her body, leading to non-consensual sexual contact initiated by Rui. Subsequently, Kirei and Rui endure a gang rape by the native men. After the assault, they get cast into an oubliette. The episode concludes with Kirei and Rui undergoing a surreal metamorphosis, emerging from the pit transformed into butterflies.