Jimoto no Ijimekkotachi ni Shikaeshi Shiyou to Shitara, Betsu no Tatakai ga Hajimatta.

As a child, Kotaro was humiliated by a group of bullies, Akira, a wrestling prodigy, Kanae, a basketball prodigy, and Sigure, a gamer prodigy, who would beat him at anything they tried. Now in high school, Kotaro is reunited with those three bullies, and he swears he will get back at them this time…!? It's a romantic comedy about taking revenge on bullies! (Source: Kodansha, translated)