At Tokiwa Middle School, Sakurai Natsumi's older brother was well-known for being the highly respected former captain of the track and field team. However, his successor, Yoku-senpai, was a natural athlete who excelled in any sport he attempted. Despite deviating from the previous captain's methods and practicing basketball and soccer instead, Yoku-senpai was highly regarded by his peers. Natsumi was irritated by this and declared that she would boycott training if nobody else was interested. One day, when some former track and field members who disliked Natsumi's brother attacked her, Yoku-senpai came to her aid. This gesture caused Natsumi to gradually develop feelings for him. However, Natsumi's situation was complicated by the possibility of Koushi, Yoku-senpai's friend, also harboring feelings for her.
