Saving 80,000 Gold in an Another World for Retirement - Chapter 301

He became a teacher at the best magic academy in the empire.
….For being mistaken for someone else.

Nagasawa crossed to Naruto Universe and was bound to Konohagakure.If Konoha is severely damaged and destroyed, Nagasawa’s lifespan will be reduced.He panicked at the thought of the upcoming Nine-Tailed Demon Fox's attack , and the thought of Konoha getting destroyed left him in despair.Fortunately, while bound to Konoha, he can obtain templates of powerful characters.At the beginning, He got the Whitebeard template! Since it's the Whitebeard from the Summit War of Marineford, he can use Tremor-Tremor Fruit's ability and Haki.Facing the Tailed Beast Ball, which terrorized Konoha Shinobi, Nagasawa leaped and shattered the Tailed Beast Ball with one punch!

In the rebirth, in order to prevent the tragedy of the previous life from happening, Bai Yu decided to rush to the [Tower of God] at any cost, and face everything together with his sister!

However, Bai Yu, who was bound by the system, mutated his bloodline, and transformed into a black-scaled python seems to be developing on a completely different path from his previous life…

- Description from novelbuddy

The world’s top level hacker, Shi Lei; due to him hacking the world’s top military powers during a joint exercise and attempting to steal information from them, ultimately leads him to get sold out by his own organization. This act eventually caused his own death by a missile bombardment.

God was playing a joke on him and allowed him to return back to six years ago, the autumn season of when he was still at his university. Being given another chance, plus the fact that he retained his ability as one of the best in hacking technology, Shi Lei decided to change his life! During his previous life, he was only an assassin in the dark. Although such an existence made people afraid of him, he would have to always hide within the shadows. In his new life, not only does he want to be an assassin in the dark, he also wants to stand openly in the middle of the world stage. Creating a world-class super enterprise, he will single handy change the whole world!

- Description from Novelupdates