Kana, who lives with her daughter and her husband, is frustrated by her husband's lack of sexual desires due to his work. Then she finds out that her son-in-law, Taichi, is also sexless and masturbates every night... Kana is Kokoro by his enormous cock and tries to do whatever she can to help him. Taichi can no longer resist his mother-in-law's bold seduction, and before he knows it, he can't live without her...