Jimoto no Ijimekko-tachi ni Shikaeshi Shiyou to Shitara, Betsu no Tatakai ga Hajimatta.

From Kadokawa: Local bullies tormented Kotarou when he was a youngster. They were the skilled wrestler Akari, Kanae, a basketball prodigy, and Shigure, a prodigy in video games. Every day, Kotarou competed against these three guys in their respective sports to win. Unfortunately, he was no match for them. As a senior in high school, Kotarou now has another opportunity to confront them and exact his retribution. But he will discover a secret that he never would have expected.