Jinsei Gyakuten: Uwaki Sare, Enzai o Kiserareta Ore ga, Gakuen Ichi no Bishoujo ni Natsukareru

At the end of summer, Eiji Aono witnesses his childhood friend and girlfriend, Miyuki Amada, cheating on him with Kondo, the ace of the soccer team. Betrayed by her and emotionally shattered, Eiji becomes the target of baseless slander and harassment. Cornered and with nowhere to turn, he escapes to the school rooftop—where he meets a mysterious girl...

(Source: Kadokawa, translated)