The Newt and Demon - 6.66 - The New Metal

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.

Failing in his job hunting, Sanada Kyouichirou was hopeless in this society. When kyouichirou had thrown himself towards the bottom of a cliff. When he woke up his body had returned towards when he was in fifth grade of elementary school. He did not want to have any regrets in this life so he had decided on building up an harem in this second life.

The elder sister that he admired, a senior and president of the student council at a school for rich young girls, a strong minded upper classman at school. The poison fang of Kyouichirou who had pretended to be a innocent child attacks those girls.