Ichika was not satisfied in body or Kokoro with sex with her self-centered husband. One day, while Ichika was chatting away with Yumiko, the mother of the Takada family next door, her son Tatsuya appeared. Ichika was surprised to see Tatsuya transform into a grown man since she hadn't seen him for a while, but Yumiko still treated him like a child... Feeling sorry for Tatsuya, Ichika accidentally saw him masturbating and realized that the lower half of his body had completely grown into that of an adult...