Anyone knows what is that?

Japanese oden, probably the kitchen's pot not meant to be served. Divided so they can easily get specific ingredients for serving

https://www.justonecookbook.com/oden/

Oden. A popular staple in Japan Convenience stores.

Also known as 黑輪 in Taiwan.

Some kind of hotpot. In the pot with wall. So you can store multiple different soup type in same pot.