Akademii no Kenjutsu Shinan ni Natta

A deceased web novelist is given a wish in the afterlife and chooses to enter a fictional novel. Rather than becoming the main character, he takes over the body of Kang Shin-Hyuk, a minor character. Assigned to become the protagonist's future mentor, Shin-Hyuk plans to use his knowledge of the story to take advantage of the hero's future abilities for a relaxed existence. However, in a dangerous world filled with monsters, it remains uncertain whether Shin-Hyuk can maintain his easygoing lifestyle or if he will be forced to work hard once again.