Atsushi heads to his friend's house to deliver a forgotten item belonging to Ruri, his father's new wife. It's late at night and the streets are quiet. As he reaches for the intercom, he notices a note saying it's out of order. Unable to shout, he calls out from outside, but no one answers. When he touches the doorknob, he finds it unlocked. Hesitantly stepping inside, he discovers Ruri locked in an embrace with an unfamiliar man. Overcome with rage over his father's betrayal and aroused by Ruri's lewd desires, Atsushi lunges at them!