So I've completed some of the dungeons in Mooshu and don't know if the Onis will still be in there. I've started asking my friend over the phone but he doesn't know. All I need to at least is that the Plague Oni will still be in his dungeon? I need him for a quest for my storm account. (I know the title is incomplete)
If you log out or leave a dungeon for more than thirty minutes then the dungeon will reset itself meaning you have to do all of the quests within the dungeon again. I think if you complete the dungeon it will also reset after you leave, but I'm not sure. You can do a dungeon as many times as you want.