MTL - Devouring Myriad Ghosts System - Chapter 17 Xuan Cang University's duel school rules

Perhaps it is the choice of fate. As a senior otaku, Qian Lingfeng got the “steel shell system”. However, when he swept the world with the system, became a local rich man, made all kinds of beautiful women, opened a harem, and realized the ultimate fantasy of thousands of otaku, he found that things seemed far from simple!
When the end comes, biochemical zombies suddenly come down, fierce beasts are in power, bloodthirsty zerg roam to kill the world, and human lives are comparable to dirt. Where will weak human beings go in this world? Is humanity going to be extinct? Or … can an otaku save the fate of the human race?

- Description from Novelupdates

High school student Mikoshiba Ryouma was summoned to a different world in the middle of a war. Sensing the malice from the one who summoned him (a summoner of the O’ltormea empire), he uses his martial arts to run away, killing important people of the empire during his escape. After the escape, he rescues two twin sisters from the hands of thieves. The sisters who can use magic, swear to serve him as subordinates. Thus, Ryouma begins his journey on the path of the supreme ruler.

Friends, standing before you is:The Master Of Gacha;The Bug Catcher’s Bane;The Nightmare of Every Youngster;The Idol To Countless Boys And Girls;The Second-in-Command of Team Rocket;The Uncrowned King of the Underworld;The Youngest Champion In History;Master Of All Types;Luo 'The Shining Light Of The League' Yuan!

“Ding! Choose your idle skill.”“Ding! Idle complete. Language level +999.”“Ding! Choose your idle skill.”“Ding! Idle complete. Basketball level +999.”After a freak accident, Qi Ning acquires the “”Unlimited Idle”” system. But just as the system binds to him, it crashes, leaving a repair time of 999 years. However, to Qi Ning’s surprise, the system still allows him to idle, and with every second of idling, any chosen skill instantly reaches level 999.With his life now dramatically transformed, will Qi Ning’s rise from mediocrity be unstoppable?