Hokuto is Subaru's twin sister, best known for relentlessly teasing him about his relationship with Seishirou—she and Seishirou are basically in cahoots when it comes to making wedding jokes. She's got a sharp eye for fashion and is the one behind all the elaborate costumes in the series.
Her name, Hokuto (北斗), means the Big Dipper constellation (Ursa Major). It's a neat mirror to Subaru's name, which comes from the Pleiades star cluster—the two constellations complement each other, with Subaru's stars echoing a smaller version of the Big Dipper that Hokuto's name references.
Content compiled by AnimeList.moe from publicly available sources.
