Mitsuru grew up relying on his mother Shoko since he was a child. As he grew older, Mitsuru's love became more twisted, and Shoko had no choice but to accept it. One day, a memorial service was to be held at the house of his sister-in-law and her husband, so Shoko and Mitsuru stayed overnight at their relatives' house, leaving her husband, who was busy with work, at home. That night, Mitsuru was happy to be alone with his mother, and he didn't care that it was a relative's house and started to depend on Shoko. Even though Shoko knew it was wrong, she sneaked past the relatives' eyes and took Mitsuru's hard cock into her mouth.