The Main Characters That Only I Know - Chapter 432:

Ye Qiu traveled to the Great Wilderness World and obtained the ten thousand-fold return system.

By teaching or gifting the same thing to the apprentice, you can get a high multiplier crit return.

“Ding, you give your disciple a Marrow Cleansing Pill, trigger a thousand-fold crit, and get a Divine Marrow Pill.”

“Ding, you passed ten years of kung fu to your disciples, triggered a hundred times of critical strikes, and obtained thousand years of kung fu.”

“Ding, you gave your disciple the Zixia Sword, a top-grade treasure, which will trigger ten thousand times the crit and get the Immortal Sword Yunxiao.”

All the disciples: “Master is too generous. He never hides his secrets from his disciples, and he gives everything away.”

- Description from novelbuddy

In regards to the MMORPG Cross Reverie, Sakamoto Takuma boasted an overwhelming strength that was enough for him to be called the Demon King by the other players. One day, he gets summoned to another world with his appearance in the game. There, there are two people that insist “I am the real summon master.” Takuma gets slave-turning magic used for summoned beasts cast on him by the girls –

Vahn was an atypical youth. Due to a rare mutation, his blood had the potential to target and attack ailments within the human body. Touted as a universal cure, people had elevated his status above the norm and given him the classification "Panacea". In the media, he was hailed as a great hero who would usher in a new era or human wellness. However, behind the scenes things weren't so bright. Being a unique individual, Vahn spent his entire youth locked up in a lab with various scientists and research teams using his body and blood to perform endless amounts of experiments. The only solace in his suffering was the various anime and manga made available to him between experiments. He often imagined himself as the protagonist in a world of his own, finally in control of his own destiny. For years he nurtured this desire, until at the age of 14 he died when an organization had tried to kidnap him from the lab...

The story is about a man who’s opposed to the now-common practice of implanting false memories, but is one day given memories of a fictional childhood friend. This fabricated happiness torments him, but then, to his surprise, he meets her – a girl who shouldn’t exist.