Artist. Their nickname is the Japanese name of the opera piece "Così fan tutte":[https://ja.wikipedia.org/wiki/%E3%82%B3%E3%82%B8%E3%83%BB%E3%83%95%E3%82%A1%E3%83%B3%E3%83%BB%E3%83%88%E3%82%A5%E3%83%83%E3%83%86].
cosi fan tutte