The Hero has defeated the Demon King, but the Princess he meant to save turned out to be a Prince. NEETdom, here he comes, but a life of relaxation surrounded by anime is a pretty sweet deal.
Unfortunately, he gets caught up in millennia old legends, curses, and a twisted plot involving multiple Kingdoms and many dragons. Through and through, though, he'll follow a path of whimsy, even if that involves him palling it up with "villains".
Manga