How far can we fly before we have to come down? Little by little, everyone in their First Year of Junior High School has begun their transition into adulthood. However, Akane Mizutani finds her own difficulty and question towards acting mature. On an off chance, she meets Tsukino Tooru, a boy in her class with strange, mysterious rumors surrounding him. Rumors that made even Mizutani think of him as strange.

With their encounter, Mizutani finds out the truth of Tsukino and similarly odd girl, Hiki. With Mizutani and Tsukino forming a promise at the schoolyard regarding each Monday night, the story depicts the relationship and encounters with each and one another, the alienated idea of growing up, and the truth of one's character.