As the police continue their investigation, they discover a plastic tea bottle filled with water in the dressing room, match cinders floating on the water, and Tetsuyuma's silver-gemed ring. It is also revealed that all the suspects have been seen in the hotel after the sauna was closed disproving their previous theory. Conan uses his voice changing bowtie to impersonate Agasa to reveal the one waiting on the veranda was the victim and the Tetsuyuma spotted heading to the sauna was the culprit Junsaku Tansawa in disguise. Conan explains Tansawa tricked the victim into staying in the women's sauna all night in order to see the naked Mishio Natori, the heroine; This is evidenced by the bottle in the dressing room which Tetsuyuma used to stay hydrated and the match cinders used to smoke his pipe. As evidence towards Tansawa as the culprit, Conan reveals that he was completely engrossed in pretending to be Tetsuyuma that he took the silver ring without noticing.