He's known Mafuyu since childhood, part of a friend group that also includes Yuki and Shizusumi. They all went to middle school together, though now it's just him and Shizusumi at the same prep school.
Growing up, he was always closer to Shizu than the others. On the surface, he's got a rough edge to him—blunt speech, strong personality, the kind of guy who doesn't sugarcoat things. But underneath that, he's a worrier. He genuinely cares about Mafuyu, and it clearly matters to him when they manage to reconnect. Fans often note the contrast between his tough exterior and how much he actually looks out for people he's close to.
Content compiled by AnimeList.moe from publicly available sources.