Mika, lonely in her husband's absence, continues to seek comfort from her son, Shintaro. Their relationship is a secret she can never reveal to anyone. But she has another secret: she has begun seeking anal sex from Shintaro's friend, Shimada. Now addicted to the pleasure of anal stimulation, Mika receives a new proposition from Shimada, and finally her anal sex taboo is lifted. Mature beauty Mika Matsushita experiences an entirely new kind of pleasure unlike anything before.