Former Interstellar Mercenary In Urban Cultivation World - Chapter 1355: The Seeds of Doubt

A ring-shaped bio-computer produced in 3009 AD, traversing the space and time onto Du Cheng’s head, a powerful intelligent program let Du Cheng tapped into high-tech knowledge in the next millennium.

——Commerce, industry, science and technology, Du Cheng will be leading the way, developing high-tech from the future, and making himself invincible.

——From an illegitimate child who was driven out of the family to the economic leader, creating a business empire, Du Cheng’s future is the road to the ultimate glory.

- Description from Novelupdates

Another entry in what you can call the Proto Harem Series: the books written before the Harem Series that take place in the same world.

It’s about a swordswoman whose student is captured, so she goes to rescue her.

[I was reincarnated as an F-class Hunter.

…it’s a problem because they don’t treat me that way.]

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.