Demon Emperor, Run!

After spending six thousand years in the demon realm as a country dog, Xu Xiao can finally escape the System's clutches and return to Blue Star. What a terrifyingly huge bucket it was. Unexpectedly, Blue Star has already been invaded and turned into a game world, where the qualified can travel through the Myriad Worlds. Xu Xiao only wants to quietly uncover the truth behind it all, but is mistaken on the spot for a reclusive master and swept into the turmoil. Demon summoner, body-tempering fanatic, cold-blooded killer, top-ranked bounty hunter, secluded master: he soon acquires countless awe-inspiring titles. Xu Xiao doesn't want any of them. There's only one thing on his mind. There is definitely something wrong with this System! Little monsters, take down the System for me!