Super Shen

Following a disastrous alien invasion, Earth's continents were disrupted and completely reshaped. Driven back, the aliens threaten to return in full force, but Earth itself is torn apart by power struggles among the numerous tyrants who govern it, each more ambitious than the last. Almost all of the Shen Masters perish. The most heroic among them, the Savior, disappears without a trace. Remaining are the Northern Sovereign, who takes the lead of the Northern Empire and turns it into an advanced and peaceful state, and Lord Mars, who commands the Eastern Island (corresponding to the East); the Southern City is instead a barbaric and primitive world, while the Western World is a totalitarian state. The only hope for future revival lies in Wugy and Daygo, the two sons of the mighty warrior who repelled the alien threat!

(credits https://www.animeclick.it/manga/11863/super-shen)