It started when Kogoro and Ai were shocked and enraged at the news of Ryusuke Higo and Yoko Okino going out. Therefore, Ai "hires" Kogoro to conduct an investigation about them. While searching on the internet, they find out that the couple were spotted at a restaurant in Haido City. Conan then says that there's a new restaurant in Haido City which belongs to a senior of Higo. The two force Conan to take them there to spy on the couple. Haibara even goes as far as deleting the song Dandy Lion from her phone, even though it's her favorite song.
Teiya Asuka, Higo's senior and the owner of the restaurant has gone missing. The three employees, namely Yasuto Konoe, Reiko Banba and Akimichi Yamada, have to go look for him. Konoe later receives a message from the owner, saying that he is in the storeroom and want to meet Higo and Yoko there. But when the couple arrives at the storeroom, they find Asuka dead, covered in blood!
Inspector Megure reviews all of the suspects movements before the murder. Kogoro continues to try to blame Higo so Conan tranquilizes him and reveals that the culprit is Akimichi Yamada. Yamada killed Asuka because Asuka had discovered that he was a fraud who wanted to expand the business with the extra money he'd accrued by buying cheap wine that he presented as expensive.
He killed Asuka during the second search when he went down to the storage room, then used Higo's and Asuka's phones for the trick, as well as a vacuum, a vacuum compression bag, Asuka's clothes, and the corkscrew from his sommelier's knife. Ai finds Higo's discarded phone and the vacuum bags to provide the evidence. Other hints to Yamada's faked profession as a sommelier were provided when
Yamada did not sniff the cork of the wine bottle he had served Higo and Yoko, something a real sommelier always does in order to find out whether the wine has been spoiled by residual chemicals used in making the bottle corks
and the fact that the cigarettes found in the toilet were of the same brand, but smoked in two different ways, proving that they were consumed by two different people.
Higo and Yoko are not dating each other—the watch they were looking at on the cover of the tabloid article was a mutual gift for a retiring high school teacher of theirs, and they were meeting with Asuka to ask him to write a message on the watch.
Ai is thanked by Higo for finding the evidence, and says he's tempted to have her take Takahiro Sanada's place on Big Osaka. The next day, Ai seems determined to prove herself a soccer player, and is enjoying Yoko's music again.
Season 24 (2019)