Steel, Explosives, and Spellcasters - Chapter 398 - 44: Turu, Haug, and Naiman

A man who was once called the world’s strongest agent ended up becoming a teacher after his retirement, to train a new generation of agents. After many years of training his disciples, he was killed at the age of 60 by a secret organization’s ruse and was reincarnated in another world with his memories intact. Though he was surprised by the existence of magic and the strange species in that world, he quickly adapted to his condition as a newborn and took advantage of it. He acquired special magic and gained a massive amount of strength thanks to his rigorous discipline, in order to reach his goal: Resume his career as a teacher which he left halfway through in his previous life. This is the story of a man, who, based on the memories and the experiences of his previous life, became a teacher who travels through the world with his students.

Before his death, he was the only sword cultivator in the whole world, who dedicated his entire life to the path of sword immortality.

When he opened his eyes again, the world had completely changed. He began to cultivate the path of sword immortality again, slaying the heavenly way, shattering the universe with his will, and achieving the realm of sword immortality!

- Description from Novelupdates

When he woke up, there was actually a beautiful CEO wife of Queen Fan.

Kira was living the life that others could only dream about. He was gorgeous, rich and very popular - the kind of guy that drew students from all over the place just so they could brag to others that they went to the same school as him. He was undoubtedly the number one heartthrob that every girl dreamed about.