Ichiban Ushiro no Daimaou - Volume 2, Chapter 3 — The Three Keys

This is the story of a person who transmigrated into a world with a radically different worldview.

A former sporting rifle shooter genius transforms into the ‘Juvenile Butcher’. While originally supposed to have received the death penalty, he was instead fortunate enough to have entered a secret and highly regarded armed force, throwing himself into the ‘Nirvana Project’.

After a period of 10 years, he now has time to freely recover. Having trained until he had excellent military and martial skill, he sweeps through various military districts and returns back to his hometown. Under the monitoring of a beautiful female cop, he re-establishes his family’s bodyguard service, protecting beauties and moving unhindered, his achievements causing the fame of his outstanding, god-level bodyguard service to resound across the world!

- Description from Novelupdates

A Consort seeks prosperity.A Shepherd cloaked in yellow wages war.A Prosthesis-wielder cries out for retribution.Shadows tremble in the depths, encompassed worlds obscuring the many dangerous secrets of history. Might they be unraveled, all ways of life would be threatened. But to climb higher requires risks, to seek the light requires a Gambit of Lifetimes.Only when one determines themselves capable of risking it all, can all prosper.

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 –