Toshio's girlfriend Yui visits Toshio's house. Toshio's brother Hikaru meets Yui and finds out that she is a de M. Hikaru, who planned to train her Yui, stares at Yui and treats her gently. One day, when Toshio was not there, Yui came to her house to pick up her forgotten item, and received tea from Hikaru, which she spilled on Hikaru's crotch.
