Kamisama Kiss Vol. 18 (manga)

Nanami's journey to the past was a success! She found a way to break the curse and save Tomoe, and he even admitted that he has feelings for her. Now they're both ready to enjoy life as a happy couple. Tomoe is hoping to spend some special alone time with Nanami, but instead they go on a school trip to Okinawa with the entire grade--and things go from tropical paradise to yokai nightmare in no time!