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 Demizu, 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. Yamashita appears to have been killed by someone while eating sushi delivered from a restaurant.

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 Kawakami, 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 and his friends are asked by an elderly woman, Yamada Fusae, to search for her grandson, Kohei, who has borrowed money from a loan shark and is on the run. According to Fusae's story, Kohei is trying to kill someone. Fusae stays overnight at the office and watches over the search while cheering up Seiya and the others with her signature dish. Meanwhile, Kyoko believes that Shizuo Matsumoto, the don of the money-making world, is Fusae's first love, and arranges a reunion. Fusae learns of this and begins preparing food with a smile on her face. However, Kohei's found story reveals that Fusae is trying to poison Matsumoto, who is tormenting Kohei.

A series of murders of female pastry chefs occur in Yokohama City near Valentine's Day. Seiya arrives at the scene and suspects that a cake left behind may hold the key to solving the case. On the back of the cake, there is a pattern that looks like an inverted “4” combined with a number of horizontal lines. Momo learns that the two victims are graduates of the same confectionery school, and she becomes increasingly wary, deducing that the patissier who made the cake that was left behind will be the next target of the murder. Meanwhile, Seiya watches as Kyoko makes homemade chocolates, and realizes the secret of the cake at the scene -- it was made by a pastry chef.

Seiya and his friends are asked by Nonomura Shigezo, the chairman of a restaurant chain, to find a croquette they remember eating 20 years ago. However, the Raccoon Bridge shopping district, where the croquette store Kameya used to be, has been hit hard by redevelopment, and the store has moved to a new location and is nowhere to be found. Kyoko tries to gather information via the Internet, but she begins to receive phone calls threatening to stop her search for the croquette store, and she begins to receive unwanted phone calls. After consulting Momo and Igarashi, Seiya and Ryosuke learn that there was an incident 20 years ago in which a man fell to his death in the Raccoon Bridge shopping district, and that Kameya was involved.

While a murder is connected to the robbery of the sacred jewel, Seiya attends a week-long free class visit with Kyoko at the request of the Kindaichi boy. Seiya's goal is to have a delicious school lunch. However, when Seiya notices that the children have many likes and dislikes, he tells them the story of the “Mottainai Ghost” and stresses the importance of food. A security guard testifies that he saw a suspicious figure in the school building at night. Rumors spread that it was the “Mottainai Ghost". Kindaichi is asked by his favorite girl, Rei, to find out what it is.

A murder case is reported in which drugs are believed to be involved. From the conditions at the scene and the remains on the victim's clothes, it becomes clear that flour is involved in the case. Seiya, who uses his famous tongue to recognize the flour as okonomiyaki flour, goes to several okonomiyaki restaurants in the vicinity of the crime scene and notices the murderer at one of them. He realizes that the culprit is in one of the restaurants. Eventually, Seiya, Ryosuke, and Kyoko are trapped by someone and locked in a warehouse, where they find a time bomb with 10 minutes remaining... When they fail to disarm the time bomb, they find themselves in a desperate situation!

Seiya disappears into the sea as a time bomb explodes. Ryosuke, realizing his fate, vows to take revenge on Seiya and starts following Yuki, the most suspicious of all. However, Yuki disappears near a cabaret called “Parry” as if he sees through Ryosuke's movements. Meanwhile, a returning Kindaichi boy brings a dancer who looks exactly like Seiya, dressed in a flashy fashion. The man's hobbies and tastes are completely different from those of Seiya. Ryosuke learns that the man dances in “Parry” and becomes interested in him. The drama soon takes place on a luxury cruise ship sailing from Yokohama. Who is this man who looks exactly like Seiya? Is Yuki an enemy or a friend? Will the owner of the office reveal himself? And what about Seiya Takano, the eater of food? A lot of highlights! A 15-minute extended final special full of tears and laughter.