Yuki's mother, Chisato, is a single mother who divorced 15 years ago. Chisato worked hard to raise Yuki well, and he graduated from college and grew into a respectable member of society. Yuki bought Chisato a trip to a hot spring with his first paycheck. Chisato was really happy that Yuki had invited her on the trip, but she also felt a little lonely, as it seemed her role as a mother was over...