Dakara Bokutachi wa Osananajimi wo Yameta.

We were childhood friends back then. Tomoe Yako, Takehiro Furuya, and Kyotaro Mikagami The three of us, who lived near each other, always played together in good harmony. However, by the time they graduated from junior high school, Tomoe had emerged as a pianist and Takehiro as a karate fighter, creating a big gap between them and Kyotaro, who had nothing... One day, Kyotaro was told, "You shouldn't get in the way of those two," and he realized that he was a hindrance to them. He spent his high school life trying to keep his distance from them and avoid them. But on the day of graduation, Kyotaro goes to see them and what does he see? The gears of their childhood friendship are becoming more and more twisted, and where they will end up--!

(from mangaupdates)