Touhou Project (東方Project) - Komano Aun by Daniel Renard

Only some of them are little girls, most of them can be considered adults… I think

There's a whole meme about Yuyuko, Yukari, Eirin, Kanako and Byakuren(amongst new additions like Junko) being a hag alliance for looking older than the rest of the cast so you're kinda right.

Most of the cast looks like late-teens though.