Mihina and Mei, two close friends like sisters, gradually develop an intimate relationship through touching each other's bodies in their daily lives. One day, while Mihina is giving a massage to Mei, who has hurt her back, a lecherous coach suddenly appears. The coach instructs Mihina and suggests directly massaging the lying-down Mei. Though shocked and angered, both girls find themselves drawn into the coach's unsettling behavior. Later, they discover him changing in a room and notice his crotch is visibly aroused. When they confront him, he refuses to admit anything. Yet, Mihina and Mei slowly begin to sense a dominant, sadistic side in the coach. Teasing, suddenly attacking him, and even licking his crotch together, the two girls dive deeper into a sexual relationship with him. Will the coach's actions become the catalyst that changes them forever? Should he be condemned—or thanked? The answer is left to the viewer.