Well, from the title 'the max level hero returned novel', it could be a story where the hero, having achieved the highest level of power or ability, decides to come back. This return might be to his hometown or the place where his adventures first began. He might be on a mission to right some wrongs that happened before he reached the max level, or perhaps he's looking for a new purpose now that he's at the peak of his powers.
I'm not sure specifically as I haven't read it in detail. But generally, it might be about a hero who has reached the maximum level in some sort of game - like world and then returns. Maybe he comes back to his old haunts with new powers and has to face old enemies or new challenges that have arisen in his absence.
The 'the max level hero returned novel' probably tells the story of a hero who has ascended to the highest level possible in a particular realm, be it a virtual game world or a fantastical universe. His return could stir up all sorts of things. For example, the power balance in the place he returns to might be disrupted. People might fear his power, or there could be those who want to use him for their own gains. There could also be a personal journey for the hero, like dealing with his past relationships or memories now that he's back as a max - level entity.