I Am a Rune Engraver, Carrying a Knife Makes Perfect Sense - Chapter 1 - The Little Rusty Knife

On modern-day Earth, An Lin seems to have been abandoned by God.
When his father suddenly disappears, An Lin is left with his father’s immense debt, putting his life at risk.
After being forced to a rooftop by his pursuing creditors, An Lin is unexpectedly swept off his feet and brought to the ground safely.

After learning that he was saved by an Immortal, An Lin is gifted, seemingly out of pure generosity, the ‘God Of War System,’ and a pass to a new realm.
Follow An Lin as he experiences a whole new world of legends, meets many new friends, acquires legendary weapons and tools, and starts on his path of becoming a powerful cultivator. There is never a dull time in An Lin’s new life with his ‘great’ new system!

- Description from Novelupdates

A man who was once called the world strongest agent ended up becoming a teacher after his retirement to train the new generation of agents. After many years of training his disciples, he is killed at the age of 60 by the ploy of a secret organization and was reincarnated in another world with all his past memories.Though he was surprised by the magic and the strange species of that world, he adapted very fast 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 tight 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 new students.

Jason was just an ordinary student at Westwood University's Hunter Department, known for never awakening any special powers—even at 21. Frustrated and desperate, he spent countless nights dreaming of finally unlocking his hidden potential.One lazy morning, as he lay in bed dreading another day of ridicule, Jason felt a strange surge of excitement. Without warning, he awakened a bizarre but thrilling power: the “Leisure Life.” His smartphone buzzed with a mysterious app, and curious, he tapped it open.In a flash, Jason found himself exploring abilities he never imagined—like using points to enhance his body or entering worlds straight from adult videos. Determined to test his newfound powers, Jason dove headfirst into the explicit world of JAV, a video he'd secretly watched only days ago.Life was finally about to get exciting.