Detective Conan Episode 406 — Ad-Free

The episode begins on a peaceful, rainy afternoon. Ran Mouri is cleaning the agency when she notices Conan Edogawa staring out the window, deep in thought. Kogoro Mouri is, as usual, sitting at his desk with a can of beer and a horse racing newspaper, grumbling about his losses. Ran scolds him for being lazy and not having any clients.

Conan, using his voice-changer bowtie (but as himself, not as Kogoro yet), points out: "If he crashed or got lost, why would he take his locket but leave his briefcase and car keys? It doesn’t make sense." Kogoro, annoyed as always, dismisses Conan’s comment but secretly agrees. Detective Conan Episode 406

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. The episode begins on a peaceful, rainy afternoon

They search the surrounding forest. About 200 meters from the car, hidden behind a thick bush, they discover a narrow, overgrown trail leading to an abandoned, decrepit shrine. Inside the shrine, they find more clues: a discarded, empty bottle of sleeping pills, a woman’s hairpin, and a man’s muddy shoe print. Ran scolds him for being lazy and not having any clients

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.

Conan pieces everything together. He uses his tranquilizer dart on Kogoro and reveals the truth in his "Sleeping Kogoro" voice.