Hidetoshi, a ronin student, is a mama's boy who is in love with his mother, Kaori, who is kind and devoted to her family. One day, Kaori goes out for the first time in a while, which makes Hidetoshi wonder, and he learns that she has started going to the gym. However, when Hidetoshi sees her furtively talking on the phone, he becomes suspicious of her and secretly follows her, only to witness her disappear into a young man's house. "Mom, you're a liar!" Kaori, unaware of what has happened, is about to go out again, but Hidetoshi accidentally pushes her down...