Mion's the oldest in Keiichi's class, which makes her the natural choice for class president. Everyone basically defers to her leadership, and she clearly respects Keiichi as both a friend and rival—though it becomes pretty obvious later that she's got feelings for him beyond that.
On the surface, she's all tomboy energy. She'll call herself "oji-san" (old man) and lean hard into that rough persona, but there's definitely a softer, more girly side hiding underneath. As the next in line to run the Sonozaki household—one of the Three Families that basically runs Hinamizawa—she's got serious family weight on her shoulders.
Fans often note the holstered airsoft gun she usually carries around, though she's never actually shown firing it (the PS2 version dropped it entirely). What she *is* genuinely skilled at is martial arts. That's where her real edge comes from.
Mion runs the after-school club, which is just the main cast hanging out together. She's obsessed with organizing strategy games with actual stakes—losers have to wear embarrassing, overly frilly outfits on the way home. The thing about her games is that she doesn't play by the book. She'll mark the deck, use charm to psyche out her opponents, whatever it takes to win. It's all pretty underhanded, but that's kind of the appeal.
Content compiled by AnimeList.moe from publicly available sources.
