Now Mikuru-chan, take off your clothes! - S1.E11

Yuki hides Ryoko in a little box before Haruhi, Mikuru and Tsuruya come over to make Valentine's Day chocolates. Haruhi's plan to make a life-size chocolate Mikuru is deemed impossible, so the remaining chocolate is fashioned into smaller sculptures, truffles, and small chocolate cakes. Once the 3 girls leave, Yuki lets Ryoko out of her box, and shares a chocolate cake with her.