Be Gentle, Immortal Master - Chapter 231 - Mandatory Vacation

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.

Shi Hao, a young man, managed to turn the tables on a powerful figure trying to possess him. He gained countless cultivation techniques, martial skills, formations, alchemy knowledge, and talisman arts, setting him on a legendary path.Now, every genius and tyrant must bow before him.Those who refuse? They'll be eliminated!

This is a story of a little man who walks forward silently, in awe, and strives to chase his dream.

- Description from novelbuddy

The one single goal in life of the Strongest Old Sage is to subjugate the Demon King. In an epic final battle, both of them met their mutual destruction at each other’s hands.

However, the Demon King was not completely destroyed!

In order to destroy the Demon King once and for all; post-death, the Old Sage trains in the World of Gods and reincarnates as the Apostle of the Gods, Will.

In the reincarnated future, the Old Sage had become a legend and his former disciples hold the supreme authority in the world. The disciples had created an organization to oppose the Demon King and an academy to nurture the new generation of Heroes.

Thus the Apostle of the Gods, Will (8 year old), enrols into that Academy of Heroes.

This is the story of a boy on a mission to save the world through epic battles while enjoying Academy life.