Atsushi heads to his friend's house to return something that his father's new wife, Ruri, left behind. When he presses the intercom, he finds a "out of order" note on the door. Because it's the middle of the night, he can't yell too loudly as he tries to call out, but there's no response from inside. He has no choice but to put his hand on the doorknob, only to find that it's unlocked. He cautiously peeks downstairs and finds Ruri and a man he doesn't know embracing each other... Atsushi pounces on Ruri to relieve his betrayal of his father and Ruri's lustful sexual desire!