Zenith Online: Rebirth of the Strongest Player - Chapter 574 Reasonable Advice

Childhood sweethearts.
The most popular person in school is my childhood sweetheart.

- Description from Novelupdates

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.

«Ding! You’ve received the [Human Archer (Stage 2)] and has activated the 10,000x bonus. You have received the [Flame God Archer (Stage 10)].»

Six months ago, tens of thousands of black phantom towers appeared all over the world, floating above the cities. Chemists, physicists, religious people… all of them could do nothing.