Kogoro (via Conan) reveals that the locket is the key piece of evidence. It is not at the crime scene, and when the police search Yukie’s house, they will find it hidden in her jewelry box. Inside, besides Miyuki’s photo, there will be Keisuke’s fingerprints and, more importantly, traces of the sleeping pills from his system that transferred onto the locket when she removed it from his neck.
She then went back to the car, smashed his watch to show 2:15 PM (the time she wanted to fake), took the locket as a trophy, and drove back to the city using a back road. Her alibi was airtight because she had carefully planned the timing—the drive from the mountain to her friend’s house and the supermarket was exactly 90 minutes, which she accounted for by leaving the shrine at 6:00 PM, not 7:30 PM. She had set Keisuke’s car clock forward by 5 hours earlier that morning, so he arrived at the shrine thinking it was 2:15 PM, but it was actually 7:15 PM.
Yukie explains the circumstances of her husband’s disappearance. Three days ago, Keisuke left their home in the morning saying he was going to visit a construction site in the neighboring city. He took his car. He never returned, and his phone has been turned off since that afternoon. The police tracked his car’s GPS, but the signal was lost in a remote mountainous area on the outskirts of town. Detective Conan Episode 406
Kogoro, intrigued by the mystery of the locket and the disappearance, agrees to take the case. Conan, however, is already suspicious, noticing a slight hesitation in Yukie’s eyes whenever she mentions the locket.
Conan then looks into the locket. He asks Ran to investigate Yukie’s past. Ran discovers that Yukie had a younger sister named who died in a car accident ten years ago. In the accident, a drunk driver hit their car. The drunk driver? A young, promising architect named Keisuke Sonoda. Kogoro (via Conan) reveals that the locket is
As they are about to leave the shrine, Conan notices a faint drag mark on the ground leading further into the woods. They follow it to the edge of a cliff overlooking a river. There, tangled in the roots of a tree hanging over the cliff, is a man’s jacket. Kogoro pulls it up, and a wallet falls out. Inside the wallet is Keisuke Sonoda’s driver’s license.
Ran, watching, has tears in her eyes. Conan, however, remains stoic but somber. He concludes: "The locket was supposed to be a memento of atonement, but it became a motive for murder. A coincidence of timing and hidden truths." She then went back to the car, smashed
Suddenly, the doorbell rings. Ran rushes to answer, hoping for a client. A well-dressed, distressed woman in her late twenties stands at the door. She introduces herself as . She explains that her husband, Keisuke Sonoda , a successful architect, has been missing for three days. She has already contacted the police, but since there’s no evidence of a crime, they have only issued a missing person notice and are not actively investigating. Desperate, she has come to the famous "Sleeping Kogoro" for help.
Initially, it looks like an accident or suicide. But Conan notices the critical contradiction: Keisuke’s watch is broken, showing the time of 2:15 PM, and the date on the watch is the day he disappeared. However, the pathologist later confirms that the time of death was around 8:00 PM that evening. If he fell at 2:15 PM, he couldn’t have died at 8:00 PM. Therefore, the watch was smashed deliberately to mislead investigators.
He explains: Ten years ago, Keisuke Sonoda caused an accident that killed Miyuki, Yukie’s sister. Keisuke was never criminally charged due to a lack of evidence that he was driving, but civilly, he paid a large settlement. He later met Yukie, who apparently did not know his connection to her sister’s death. They married.
However, the locket Keisuke always wore did not contain a picture of a childhood sweetheart—it contained a picture of , the girl he killed. He wore it as a constant reminder of his guilt, a promise to himself to never forget the life he took and to live honorably.