Trying to find a certain episode/movie

Okay so. This is all based on memory so some details may not be perfectly accurate.

A long time ago, I vaguely remember going to a local art class in Korea and we were watching something animated with a small kid and a bunch of older people and there was a dead guy.

Now I'm heavily suspecting that this was Detective Conan but I can't remember which movie or episode it came from

There was a train or vehicle with private sitting stalls like the Hogwarts Express. There was a sliding door to the compartment. The one I remember had like the sliding chain bolt locks where you have to grab the bolt and slide it into the lock. I remember a scene where some girl like kicked against the door, the chain shattered and the door opened and there was a dead guy. I'm like pretty sure it might've been a gun shot wound since there was a scene where someone shot a gun?

I remember a kid with glasses on. That's the main thing.

If anyone could help out that would be great! It won't be any movie/episode that released from 2020-2024 for sure. It's some episode or movie from before 2020.