Hayate the Combat Butler 15 features story and art by Kenjiro Hata.

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!