With his parents away on a trip, Koji was left home alone. Out of concern, his mother's close friend, Miki, began stopping by occasionally to check on him. Unbeknownst to her, Koji had long harbored romantic feelings toward Miki. Amidst the mundane routine, a wicked desire grew within him—to create adult memories with Miki. One day, he sneaked into the changing room to use her underwear as a masturbation aid, but unexpectedly ran into Miki herself. Shocked by the turn of events, Koji braced for anger, but instead of scolding him, Miki pressed her body against him and whispered, "You wanted to do something like this with me, didn't you?"—ushering their relationship into bold, uncharted territory.