There are people under there. Fans of the anime Love Live. They're called "Love Livers" (ラブライバー or rabu raibaa) for good reason, because they really, really adore Love Live.
These, however, are not. Obviously, these are the far end of the spectrum and your typical Love Live fan does not dress like this. Yet. Wherever will it go from here? Who knows!
Top photo: vicks2054