Given that Miku's nails are red, Teto's color, I hope that Teto's nails in this image are teal. Because, even if I personally don't care for painted nails, it would be really cute to have them wearing their girlfriend's respective color.
Eh, but I am probably just being biased after seeing more Teto Yuri. Even though I wish it was with Ruko as that is my favorite Yuri pairing in Vocaloid and UTAUloid.