In-Chara na Ore to Ichatsukitai tte Maji ka yo......

A gloomy boy, Shizuki Kujou, quietly endures his student life. However, suddenly, the most cheerful girl in school, Yona Kasuga, confesses her love to him! He's fed up with her happy-go-lucky attitude and turns her down, but she declares, "Please change me into the ideal gloomy person!"

(Source: Kadokawa, translated)