I don't remember but it is a manga/manhwa where the MC is transported to another world but cannot go back to his world after defeating the demon king and is stuck in a loop so he tries all the things but at the end, he summons another hero to break the loop. And turns the demon king into a female...

In I'm in Love With the Villainess, Rae Taylor was once an overworked office worker named Rei Oohashi before being reincarnated in the world of Revolution. I realised recently that, while Rae and Claire are physically the same age, Rae must actually be a few years older - at the very least, Rae c...