Megurine Luka, Hatsune Miku, Kagamine Rin and Len are all part of the second installment of Vocaloid, a voice synthesizer that has hopeful song writers create several Japanese songs in different genres. Miku was the second to be released in the series, followed by Rin and Len, and finally Luka.
I’m wondering why the girls are all wearing similar outfits. Is this from another song I have yet to hear about? Thanks to Padme for sending this!