Momoko, a mother, has been devoting her life to her beloved son for 15 years since separating from her husband, refusing to remarry. One night, she hears moaning coming from her son's room. Momoko then spies on her beloved son having sex, and is overcome by Kokoro rather than joy that her son has grown into a man. From that day on, Momoko's attitude towards her son changes completely. Despite struggling with the barrier between parent and child, Momoko is unable to suppress the sexual desire that has been building up for 15 years, so she sneaks into the bathroom while her son is taking a bath...