Seventeen-year-old Asamura Yuuta is a talented young boy. He lives alone with his father and often works evenings to save money for his future studies. One day, he learns that he will soon have a stepsister, as his father recently met a woman with whom he feels happy, and they are planning to live together soon. Although Yuuta is understanding, he isn't quite sure how to approach the subject of having a stepsister.
