Ao to Haru

This is a coming-of-age love story centered around Miyano Aoi, a shy high school girl. Soon after starting high school, Aoi catches the flu and when she is able to return to school, she finds herself alone and unable to join any group. One day, Aoi breaks her arm while saving her classmate Mitani Haru from slipping on the stairs. After that, she begins to interact with the friendly and popular Mitani, and the shy Aoi gradually begins to change. https://www.cmoa.jp/title/370275/