At the beginning of episode 3, as Mikatan brings a Christmas tree into Ito's room, this conversation happens:
Ito: Wh-What is that?
Mikatan: Isn't it obvious? It's Yakushimaru Ritsuko. Oh, I mean, a Christmas tree.
Who is Yakushimaru Ritsuko supposed to be a reference to? Does the real person has anything to do with the context here?