The Divine Urban Physician - Chapter 2008 - A Real Warning

Finding himself in an Last Airbender without an airbender around, a transmigrator waterbender goes on an adventure to stop the worst from happening to him.

A boy awakens alone in the Fairy Tail world, lost and uncertain. As he ventures through this magical realm, he unravels the secrets of his mysterious new identity, unlocks hidden powers, and carves out his destiny in a land brimming with wonder, danger, and limitless adventure.“Check out my other work, Reincarnated as Ash: A Pokémon Tale.”

After breaking up with his girlfriend, he accidentally acquired a genius system and rose from there against the heavens, becoming invincible..

- Description from Novelupdates

He was the merciless Soldier King on the battlefield who sent shivers down the enemies' spines; he was the soldier scoundrel in his squad who could make anyone both cry and laugh; he was the Big Brother everyone in the urban underworld aspired to be; he was the male god in the hearts of young girls and beautiful women; he returned with a mission...Uniting the underworld, establishing an economic empire, he vowed to become the supreme overlord of this world...To prevent the world from destruction, to protect world peace, to implement love and truth's evil, the lovely and charming antagonist, he is Xiang Yu, and he speaks for himself...