Since losing his father in an accident at a young age, Sei has been raising Seimei single-handedly. Although Seimei grew up without much of a rebellious phase, he had come to love Midori more than just as a mother, as she had always loved him dearly. One day, Midori invited Seimei on a hot spring trip. She wanted to make up for never having done anything properly as a parent and hoped this trip would be their last memory together. However, Seimei was thinking impure thoughts about the trip: 'Could I sleep with Mom during this trip?'
