He's a reserve member of the Miyama family who basically works as their in-house cook—handling whatever yakuza cuisine needs to be done. His actual background is pretty different from that job, though. His family runs a small restaurant, and he himself actually went to pastry school, so he's got legit culinary training under his belt.
In his school days, he was on the basketball team. Later, from his late teens into his early twenties, he worked as a host before eventually settling into his current role. It's kind of surprising given how he comes across, but he's actually strict about respecting the yakuza's internal hierarchy and rules—very old-school about that stuff.
He doesn't have formal certifications hanging on a wall or anything, but he knows how to make the most of what he's got skill-wise. Fans often note the contrast between his polished culinary training and his yakuza lifestyle, though he seems to handle both pretty naturally.
Content compiled by AnimeList.moe from publicly available sources.