Mouri Kogoro received a letter from a mysterious person called Kurataya Komakichi saying he wanted to give him his family treasure. So, Ran and Conan decided to accompany him to Yamaguchi. The letter said: "I'll be waiting in front of the large fox at the Yuda hot springs Station at 3 PM" signed Kurataya Komakichi. He suddenly exclaimed himself that he would be rich and woke up the whole train wagon making Ran and Conan a bit uncomfortable. They later arrived at the Shin-Yamaguchi Station and again, Kogoro exclaimed himself that they arrived in Yamaguchi. Because they had plenty of time before the meeting started, they decided to do sightseeing but Kogoro ran into Natsume Asuka, a Yamaguchi news site reporter at Yamaguchi Shimbun and she gave him her business card. When she asked Kogoro why they were in Yamaguchi, he said that they were only sightseeing not mentioning the mysterious letter from Kurataya Komakichi...