Yuji studies at a private school in Tokyo. He lives alone in a dormitory. During this time, Yuji's father remarried Kana. He met Kana once when he went home. To him, Kana is more like someone he admires than a mother. Then, his graduation ceremony came, and his father was busy with work, so he couldn't attend. Kana, not wanting Yuji to feel lonely, went to Tokyo to see him. And the two went out to celebrate Yuji's graduation. Perhaps due to being too drunk, Kana expressed all her true feelings. She felt lonely because her husband was always busy with work and that she had feelings for him. And from then on, whenever his father was absent, the two no longer acted as mother and son but had become lovers...