MTL - Conan’s World Stand-in - ~ I believe, I believe very much

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.

Summary Version 1:

The mysterious boy Ling Chen is saved by a little girl as he lay on the street dying. Years later, he strikes a deal to save this savior-turned sister and enters the virtual world. In a future Earth where advanced warfare has forced nations to settle issues virtually or else suffer the consequences, Ling Chen bursts into the scene and goes from unknown to legend. Yet all is not as it seems, for Ling Chen has a dark past, and there is a greater mystery at hand behind this virtual world.

Summary Version 2:

To save his terminally ill little sister, Ling Chen enters the newly released virtual game world and joins a small gaming studio comprising entirely of women. From now on walking upon his path towards the pinnacle. An ancient, evil item almost forgotten by history, the “Lunar Scourge” helps forge his unsurpassable legend, and causes him to unknowingly step upon a path that is destined to be punished by the heavens, the way of the shura.

Callius von Jervain.

A character who dies no matter what he does. A character who falls into a forced choice route where he can only die, no matter his choices up to that point. However, there is a single route where the character can live and play the game.

And I have to carve out that route somehow.

Because I’ve become Callius von Jervain in the game.

She was framed by her sister and accidentally had a one-night stand with him. Later, he found various unreasonable excuses to force her to live with him. To seek revenge, she reluctantly agreed.“I...I thought you were gay!” She slowly retreated to the corner of the wall.“I thought you already knew the answer to that question that night,” he said, emphasizing the word “that night”.Later, to get a celebrity's headline news, she secretly sneaked into a grand engagement banquet. However...“Everyone, this is my fiancée.” He said to the guests, holding her waist. Upon hearing this, her stepmother and sister were both stunned.With his help and her own efforts, she thought she was going to live a happy life. However, her company suddenly had a new boss...“You! You eat my food, live in my house, sleep with me, and how dare you deduct my salary!”“What about that night you slept with me and only gave me $50?” He said.She thought to herself: How could a billionaire be so petty about just $50! She would definitely divorce!Six years later...“Mommy! This uncle said he'll be our daddy if we pay him just $50! Should we get him?”“Mommy! I agree with that!”