When Hajime was small, he had an older sister who he often played and slept with, even though he didn’t quite remember that time in detail. It had been many years since their parents had suddenly divorced, but one day, he was reunited with his sister and they lived together once again. Even though she was quite grown up now, she still doted on him greatly, as if to make up for lost time. Sensing an opportunity, the popular class rep and his quiet and mysterious classmate also got closer to him, and he also met a national singer-songwriter.