Shukichi Haneda is at Tokiwa Hot Springs, preparing for his shogi match for the title of Meijin. As he was talking to two women, a picture of Yumi Miyamoto fell out of his robe. When he picked up the photo, he thought back to two days ago, when Yumi told him she already through away the envelope he asked her to not open until he obtains all seven because he never called her ever since he gave it to her. After that small conversation, she stormed out of the cafe, where they were talking; when he came out, she was nowhere to be seen. As he tries to find her, a stranger watches him in a car, carrying an evil smile.

Conan and his friends go to a hotel pool where Nagami, daughter of the president of Oiso Finance, drowns to death. She had been wearing a diving tank and searching the pool for her lost necklace. Based on the crime scene, Inspector Megure believes it may have been an accident. However, the hotel bellboys claim the body in the pool suddenly appeared.