To be fair, though, the artist's choice of angles combined with their particular rendition of fantasy anatomy does make it look like it could be Luka's dick ... or even (warning: bizarre) like Miku's dick is just a sleeve that Luka is sliding into.
Ahhhhhhh!
I can't stop!
Ahhhhhhh!Oh my, Miku!
You're coming like a broken faucet!