Windy has been in the company of Yuber for a while, and even though he was not a "friend", she deemed it acceptable to at least do one pointless act on his behalf. So, shortly after the failed attempt to claim the Rune of Life and Death from the Hidden Rune Village, she approached the Black Knight.
Upon her approach, the demon looked up. "Hm…?"
"It hasn't been terribly long, but… Happy Birthday."
His response clearly contained stupefaction. "You think I have concern for human traditions?"
In order to cover up her blunder, she added, "I just wanted to see."