"You won't be stiff, I have a guest futon in the closet. Where did you think you were going to sleep?!"

Midorima's mood immediately turns sharp again, if only because Takao accepted just invitation. Merlin being involved just means Midorima isn't going to bother keeping the small dog in another room so Takao can deal with him trying to sleep on him all night.

He sure as hell doesn't have an extra actual bed for Takao to sleep in and he isn't inviting him into his, especially during Cordis.