if it's not tagged, I wouldn't know it's miku

that means you obviously don't know anything about vocaloid songs, then. i mean yes, it should have the proper tags, but any true vocaloid fan would know this is miku on the spot; the attire/pattern and apple are trademarks of the song.

@Daisu
Oh boy, not every green-haired girl is miku, and not everyone follow each song made with vocaloid (and videos with vocaloids)