Pairing: Prussia x Austria

From Hikari_Kaitou:

Prussia, a lonely college student, is talked into purchasing a Vocaloid (a human-shaped robot that sings) named Austria. He brings it home, expecting it to be cute and obedient. But when he turns the Vocaloid on, he discovers that it's demanding, conceited, and on top of all that, the stupid thing won't even sing! The more time he spends with it though, the more he decides that maybe it wasn't such a waste of his money.