I'm getting really frustrated not finding this one...f Now I'm guessing it might be an original or something on webnovel.... The first chapter is him in old European times? In a mana or magic world I guess... And I think it is a fan fic where he goes to one piece, Naruto worlds... Also it might have anti hero tag?.... Damn... I'm guessing it had realm or something "world" kind of word in its name. Any wild guesses are welcome...it's eating me from subconscious to conscious. Edit: I think MC's name in the first world was Isaac or something?... Ugh f...I thought it would be so easy to find this one....now it's f getting on my nerves everyday.