友達もおらず、教室の隅でくらい青春を過ごす中学2年生の陰キャ・吉田。

ある日、教室で話しかけてきたのは隣に座る同じく陰キャの同級生女子・時雨さんだった。

彼女は言った、「私は陽キャになるのだ!!」と！

明るい青春を過ごすため、吉田と時雨さんの陽キャを目指すバトルが始まる…！

Yoshida is a gloomy second year middle school student whose precious youth has been spent stuck in the corner of his class without being able to make any friends.

Shigure is the girl who sits next to him in class and she is as gloomy as he is. One day, she struck up a conversation with Yoshida and declared,

“I’m going to become a cheerful person!”

Thus begins Yoshida and Shigure’s battle to become cheerful people in their effort to spend a brighter youth.