MTL - Cosmic Trading System - Chapter 5 Spiritual crystal

After Reincarnating into Naruto World at the Warring State Era as an Uzumaki, Masahiko thought that he got a useless System. He lived for 48 years as a normal, below average Uzumaki Shinobi.

That changed when he finally knew how the system works the day of his 49th Birthday!

- Description from Novelupdates

A man is reborn into the world of Avatar: The Last Air Bender as a waterbender from Katara's tribe. Best of all, he was the same age as her, and he had a system with him to help.He knows the future and a system that lets him continuously get stronger by completing quests or long-term missions, as well as giving him the ability to copy abilities from others for himself. He will become invincible in the world of Avatar, even more so than the Avatar himself.

Li Xuan traveled through the world of immortality and opened the apprentice system, and both apprentices and apprentices could be rewarded for upgrading.

【Ding! Accepting apprentice Qin Yue, reward you: Innate Divine Power]

【Ding! Accept the apprentice Zhao Tian, ​​reward you: call the wind and call the rain]

【Ding! Apprentice upgrade, reward you: space shuttle]

….

Li Xuan, who accepted a bunch of apprentices, evolved infinitely in seclusion.

Ten years later, the Devil Emperor invaded and wanted to sacrifice the whole world, but no one could stop it. The disciples watched the world fall into despair in pain.

At this time, Li Xuan appeared and slashed a sword against the Demon Emperor under the watchful eyes of the public.

Boom!

The sky fell apart, the invincible Demon Emperor fell on the spot, and the entire dark world was swept away by a sword.

The disciples were horrified. It turned out that the strongest person in the world was actually the master who had been in seclusion for ten years.

- Description from novelbuddy

In the last life, Lin Yu Tong chose to fly with Shen Jun for his own happiness, whereby he ended up creating an irreparable regret for a lifetime. However, such a contribution has not been able to exchange the happiness of a lifetime. Shen was derailed and Lin Yu Tong had an accident.