Here is an idea for your book:
The MC's partner could be a royal demon, and all players that genderbend themselves will swap from in-game-character to irl self. But for them, they can only have kids through magic (they find out later on) or adoption. The MC's partner and the MC partner up to take down the demon king, while all players teach the non-players how to survive and the rules of this world. While the MC also has to juggle the problems the NPCs throw at her, but it soon becomes too much so she runs away leaving a note behind telling them to fix there own problems. She leaves with the hero group to defeat the demon king, succeeding and becomes a rulers. The hero group (each person) have the choice to stay or return to their world, but the two new royal demons have to stay and are cursed with immortality. Angered by the gods she vows to get revenge, unless they return her. The gods refused to go against the world order, and so they strip her of immortality, only for a new skill to form (reincarnation). Stuck in the loop of death and rebirth(in different races, swaps gender each time, keeps her memories of her past lives, and relearns all her skills) she has to learn to love this world and its people again.
