[krisoft]

I have the same question. Happy to prepare a PR if that is welcome.

The one I would be recommending (to the niche museums site, and also to everyone who is around) is the Yokohama Coast Guard museum.

It has a really unassuming name, I only went in because I got caught out in the rain without an umbrella in Minatomirai. Dare I say it is the best museum I have ever visited. It is organised around a single curious event: In 2001 a Japanese Coast Guard vessel encountered a suspiciously behaving fishing travel. They wanted to board them when the fishing vessel took off at high speed and started shooting at them. During the pursuit they even seen the crew wield shoulder mounter missile launchers.

Turns out it was a North Korean spy ship on a mission to raise funds by smuggling drugs to Japan. The incident ended by the Korean crew scuttling their vessel. The coast guard has raised the sunk ship and built this museum around it.

Website of the museum: https://jcgmuseum.jp/en/

More info on the event: https://en.wikipedia.org/wiki/Battle_of_Amami-%C5%8Cshima