Melancholy of Haruhi Suzumiya, Vol. 11 (Manga)

Trapped on the snowy mountain by both a storm and the supernatural forces that have cut off Yuki from the Data Overmind, Kyon is roused from sleep by Asahina slowly unbuttoning her nightshirt as she climbs into his bed! Kyon realizes it cannot possibly be the real Asahina (darn!), and though he doesn't mind the house's tricks (who would?), he and the Brigade have to crack the code and escape fast before Yuki's fever (and Haruhi's restlessness) gets out of control!