Hayate the Combat Butler 15

While cleaning house, Hayate and Maria stumble upon a heretofore unmentioned, enormous jungle-themed sauna, and promptly get lost in it. After that hot, steamy adventure--complete with misplaced articles of maid clothing--it's time to cool down, as Nagi tries to cure her insomnia with a dip in the mansion's equally massive pool. Too bad she can't swim!