If you read my first chapter you migth(surrely do) not undertood the Mark things,so i will explain it here.
I always had the idea that if there is a multiverse about Undertale so why not do it with my MC and there it is, it's not well explained but The isekai Mark talk about will be a new story that i will write when i will have no idea to what to do next. And yes the stories will be interconected but i do not want them to meet just mention them in jokes or in dreams.....Anyway that all if you have any question you can always ask me in the comments section.
Have a nice day :)