that final panel makes it hard to guess what the punchline is. Woes at the fact Hoppo can't find nice pillows like with big sis? Simple embarrassment from Ta's side? Wanting to get away but not wanting to interrupt Hoppo's fun?

nobody can refuse hoppou :D

First few panels are Hoppo expressing surprise at Ta Class coming back home with her clothes intact, for once. (Refer to her previous appearances.)
Seeing as she's fresh from the frontlines, Hoppo thinks Ta Class (her body, that is) would be pretty warm.
The little Abyssal then hugs Ta Class on the stomach despite the latter's refusal, being sweaty and all that.

(Actually, Ta Class's tummy is unusually sensitive, evidenced by her bright blush in the last panel. Hnnngh.)

Translation bump...