Chrome Shelled Regios - Volume 4, Chapter 5 — The Vow on that Day

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

The world’s worst offense, is called Love.

A 29 year old civil employment exam student wakes up in a blank white room and meets a baby angel. This baby angel informs him that he died in his sleep due to heart disease like his father and grandfather. Remembering his mom and their last conversation he says that he will take on a series of life and death tests that the baby angel offers him. From this point on he must put his life on the line and fight in the stage called ‘Arena’. And Every time he clears a test he will gain abilities and weapons to increase his strength. All to clear the tests and get his life back. This is his story of his fights in the ‘Arena’.

After an accidental death, in order to continue to live, Gu Bai had to choose to go through various wonderful books to complete tasks.

Every time he became a variety of small cannon fodder inside the story, Gu Bai’s code of conduct when completing task is – by all means, don’t be inferior, don’t be shameless, don’t be upright… hold on to a golden thigh.

… N times after transmigrating

Cannon fodder: (angry contempt) … You’re already so powerful, why are you still shamelessly holding on to a golden thigh to deal with us!?

Gu Bai: (deadpan) That… holding and holding… got used to it…

- Description from Novelupdates