That Lady person also said something about barriers. And how her barriers shift reality. So its not so much as multiple worlds in sense that he is saying this entire world is a delusion created by someone.
he reminds me of Alucard, shit the character and plot progression is insane for a story that basically revolves around only a couple weeks in actuality considering how the skeleman always gets set back in time
also my theory is that our mc is accually the writer of the book and he set all these shit up because y'know someone that can rewind back in time should be able to use some divitation aswell
but he forgot his memories because plot