Yuji studies at a private school in Tokyo. He lives alone in the dormitory. During this time, Yuji's father remarried Kana. He met Kana once when he returned home. To him, Kana is more like someone he admires than a mother. Then his graduation ceremony came, his father was busy with work so he couldn't come. Kana didn't want Yuji to feel lonely so she went to Tokyo to meet him. And they both went out to celebrate Yuji's graduation. Perhaps because she was too drunk, Kana said all her true words. She feels lonely because her husband is always busy with work, and that she always has feelings for him. And from then on, every time dad was absent, the two were no longer mother and son, but both became lovers.