Takuma Sawai feels grateful for his mother, Kana, who is working hard as a single mother. But at the same time Takuma feels attracted to his own mother as a woman. On the other hand, he also admires his aunt, Mari, who takes care of him in place of his busy mother, and begins to see her as a woman too. However, Takuma feels lonely as he is unable to interact with his mother, Kana, who is busy with work.

One day, he sees his mother sleeping on the sofa because she is tired from work. Seeing her defenseless made him feel strange. Currently she is so exhausted that no matter what he does, she won't notice it. "It's just a little bit... just a little bit..." That's what Takuma told himself...