>>70523658Mumei's hits a sweetspot because it crosses 3 distinct subcultures.
Obviously it hits an emo style that north americans are very familiar with from teens in the late 90s-mid 2000s and hits nostalgia points for people who grew up through that context.
It hits a modern culture trend where lesbians (especially in the west coast) coopt early 2000s fashion trends assembled off of thriftstore discount racks to 'signal' to one another their preferences, which obviously hits the yuri crowd and the whole twitter audience that cares about that kind of thing
And it's adjacent to an early 2010s jp fashion trend of retro-punk strongly influenced by british and american alt-fashion from the 90s.
All these things means you have a lot of different groups drawn to Mumei's outfit (and drawing fanart of it) for a variety of different reasons. Fauna's outfit is also good but it doesn't hit the same breadth, especially oversees. Unironically, Raden's design is closer to what Japan associates with goth fashion, Fauna's doesn't quite land anywhere specific for them.