Manga Yari No Yuusha No Yarinaoshi

This is a spoiler for the web novel, but he's in a fake world set up by a goddess. The story of the web novel is really different than the manga, so the goddess could be represented differently if she's shown at all. In the novel she's a manipulator who's trying to destroy the two worlds in order to gain power. She sends the sword hero back to his world and sends the spear hero to a personal dimension. It's been a bit since I read that part though so I could be a bit fuzzy on the details. I think because it's a dimension made to trap him that it would have whatever he wants but in a way that he doesn't question it. That would explain why the key characters are the same, but things related to folials would be different. This is just a theory based on some facts so I could be 100% wrong in my assumption.