Nashiko's got an unconventional living situation—her family kicked her out, so she ended up moving into her parents' old mahjong parlor, which had already closed down by that point. Her mom used to run the place, so there's a family connection there, even if it's not exactly a warm homecoming.
She didn't grow up playing mahjong or anything, but once she got into it, she actually became pretty serious about the game despite starting from scratch. Her Hiroshima accent is pretty distinctive, and she's known for having some genuinely weird taste in food—like the kind of combinations that make other people do a double take.
Content compiled by AnimeList.moe from publicly available sources.