Eroge Souls: I Transmigrated as the Wonder in an H-Rated Souls Game - Chapter 12: New Sword

A man was transported to Ancient China and eventually became a servant of a declining household without a male heir. He utilized his wits and modern knowledge to help the household and eventually become trapped in the sea of political turmoils of the period.

- Description from Novelupdates

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 –

[Complete your story by challenging countless monsters, demons, and legends]

This is the last sentence I saw before I lost my mind.

And it’s one sentence that I’m still holding on to.

That’s how the journey of killing monsters and wandering in search of all kinds of rumours began.

And it will continue.

Until the day I get out of this damn game.