How about the option of “renting a villa” as a place to stay on your trip? Centered on Zao Sansui-en, a villa resort in Zao-machi, Miyagi Prefecture, you can rent an entire villa* with an attractive natural hot spring that reflects the owner's personality.
(*All bath water in the facilities except in Sansuien is natural hot spring water except for "Kominka Higurashi-an".)