Because of work, Mitsuru has moved to Tokyo to live alone for three years now. One time he went to the doctor and found out he had a tumor in his body. Thinking he didn't have much longer to live, he took his beloved mother on a trip to enjoy the happy days before dying. The two went to a hot spring hotel together. Mitsuru has long secretly loved his mother. So when his mother got drunk and exposed her beautiful panties to him, he couldn't help but touch and explore her body. His mother woke up and stopped him, Mitsuru immediately told her that he didn't have much longer to live. Because she loved her son and wanted him to try to fight his illness, Aoi agreed. When he returned, Mitsuru went for another checkup. It turned out that it was just a benign tumor. Because the doctor's expression seemed serious, he misunderstood. After this incident, the mother and daughter's relationship became better and better. Although it was no longer life-threatening, Aoi still agreed to let Mitsuru have sex with her, even though she knew this was wrong...