The protagonist's father died when he was young, and he was raised by his mother, a nurse, as a single mother. She is kind, cheerful, and has a lovely body. She has been his ideal woman since he was a child.

He became a doctor because he wanted to be with his mother as much as possible by working at the same hospital. He says, "I'm so happy to be working in the same hospital with you".

However, the protagonist spends his days feeling depressed due to a series of difficult tasks. His mother, worried about him, invites him to her office one day when she is on duty. Lying on the bed, his mother smiles kindly and seductively, telling him that he can gain experience by using her body.