Because he was born on December 24th, and his parents named him Santa.
Rough break.
She collapses with laughter.
But no, she says, okay, it was kind of funny, but she wants to make him happy.
He says to leave him alone, he's perfectly happy the way he is.
This is a lie.
The Anime Police: ahem.
I understand that you tried to speedrun an entire Instant Girlfriend romcom in a single OVA, but I'm afraid it's not up to code.
You forgot the beach episode.