Middlesea Dungeon AU (EN)

This is a third-party fan work based on the Dungeon Hospital AU by Raonmir (@Raonmir_Tuned). I took most of character designs from the original AU, but the settings and story were newly created by me. Some elements differ from the original AU.
Dungeon Hospital AU: https://twitter.com/Raonmir_Tuned/status/1386680838134194177
This AU was originally created before official release, so story and settings about Mark did not exist at that time. They were newly added while I was organizing this document.
I don't think I can finish writing this AU, but I felt like it was waste to abandon it so I'm just releasing the settings and rough plot outline for now.
Feel free to create works based on this. Modifications or suggestions are also welcomed. I'd appreciate it if you could add a link to the original AU or this Notion page.
Also feel free to correct any awkward phrases and translation errors!