Kuitan

Ryosuke and Kyoko, who were asked by the phantom owner of the office to transport a cello, came to the food capital of Hong Kong with a boy named Kindaichi who was going to visit his father Kosuke, a trading company employee. Ryosuke and the others immediately visit the Holmes Agency in Hong Kong, where they find Seiya, who has disappeared from the Yokohama office. Ryosuke and the others were astonished to learn that Seiya had been cooperating with the Hong Kong police force using three people of the same age as themselves, Lau, Kelly, and Chan, who were all very active in the police force. Then Momo and Igarashi visit Seiya all the way from Japan and request his help in investigating an incident that occurred in Yokohama. The case is the murder of a freelance journalist named Hisashi Hayase, who was found dead on a pier in Yokohama.

When Seiya Takano shows up at the detective agency “Holmes Agency,” he is accompanied by a large amount of freshly steamed Chinese manju. The staff members Ryosuke Noda and Kyoko Idemizu, who had been informed by the owner that the new leader was coming, were puzzled by the arrival of the gluttonous and greedy Seiya, who even carries his own “chopsticks”. Soon after, Seiya and the others head to the scene of a case that a well-known detective, Shuji Igarashi, is in charge of, since he happened to help catch a man who eats and drinks without paying. The case is a murder in Yokohama City. A man named Shoji Yamashita, who ran a real estate business, was strangled to death in his home. Seiya and the others watch over the investigation led by Momo Ogata, a female detective who seems to be a career detective. Shoji appears to have been killed by someone while eating sushi delivered from a restaurant.

The body of a Chinese restaurant owner, who had been in Japan for five years, was found strangely murdered in Yokohama port. Since the autopsy revealed undigested tofu, minced meat, green onions, chili peppers, and miso paste in the stomach, the police begin to investigate a rival Chinese restaurant, believing that the victim was killed shortly after eating mapo tofu. Seiya is also asked by Chief Yamaguchi to assist in the investigation, but he is unable to identify the restaurant that makes the bean curd that matches the contents of the victim's stomach. Meanwhile, a boy named Kindaichi who comes to visit the office is mistaken for the victim's son, and he and Ryosuke are kidnapped by the culprit.

In order to win the 5 million yen prize, Seiya and Ryosuke compete in a TV quiz show dealing with cooking. Ryosuke is very excited when he finds out that Hitomi Moriyama, his junior from school, is working behind the scenes as a food coordinator. However, during the taping of the show, the host, Itsuro Kawakami, collapses in agony. The cause is a seizure caused by an allergy to soba noodles. The eyes of those around him focus on the eyes of Itsuro, who seems to have been sexually harassed by him. Meanwhile, a large diamond on the necklace of Madame Lan, an actress appearing as a guest on the show, has disappeared.

Seiya Takano, a “gourmand” who has been traveling around the world tasting delicious food, returns to Japan after seeing an envelope sent to him by someone else. Inside the envelope was a special half-price ticket to “Akatsuki”, a ramen restaurant in Yokohama that Seiya had once marveled at the taste of. Seiya loses the half-price ticket as soon as he arrives in Yokohama, and decides to go to his old “Holmes Agency” to get his mind back on track. However, the office was closed and the interior, which he could glimpse through the window, was empty. Seiya arrives at the shopping arcade with a twisted head and learns that there has been a murder at his intended location, “Akatsuki”. According to Momo, Igarashi, and others at the scene, the victim was the store manager. A container of sauce, said to be a secret recipe, was missing from the restaurant, raising the possibility that the murderer was related to a rival restaurant.

A man with a blood-stained kitchen knife in his hand enters the “Holmes Agency” at lunchtime and holds the knife to the neck of Kyoko, who is out to answer the door. Seiya and Ryosuke, who were with him, are aghast. Momo and Igarashi arrive at the front door shortly after and learn that they are pursuing a man suspected of murder. Momo and the others immediately left, but the man remained holed up in the office. Seiya discovers a stain on the man's chest, which he recognizes as having been made just after he had eaten Italian food. Momo, on the other hand, was convinced that the suspect was inside the office, and immediately dispatched a team of police to surround the area. Momo is so determined that she is willing to use special forces to force her way in if the situation should arise.

Seiya brings a young foreigner named Shiketa, whom he met at a certain teishoku restaurant, to the office. Shiketa is looking for a Japanese dish that is “pudgy and a little hard". Ryosuke and Kyoko look up the dish on their computer and deduce that it is stewed pork cubes. After making various flavored pork stews and having them taste them, it became clear that Shiketa was looking for a Japanese-flavored pork stew with a strange chewy texture. At the same time, Chief Yamauchi is visited by Raymond, a consular official from an oil-producing country, who asks him to urgently look for a prince who is apparently in Yokohama on a private visit to Japan. According to the story, the prince, who is the next king of Japan, has some disturbing activities around him that are aimed at his life. Momo and Igarashi, who were told that the prince is a top secret and given his portrait, immediately set out to search for him.