MTL - Miracle Throne - Chapter 421 Underground world

This is an Isekai styled story, written from the point of view of the protagonist.

Discover the secret of the new, unknown world with Peter, as he sets his first steps in an empty, ruined city. Meet new people from all around the globe. Fight, laugh, and cry.

The story is about a boy entering high school, who answers a strange call from a public phone one night. The caller challenges him to a bet: She’ll remove the birthmark which he sees as the cause of so many problems, and he’ll have fifty days to win the heart of a girl he’d considered far beyond his reach. And with this, a very strange summer begins.

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

Fate, a gatekeeper who had been working for the castle, is beset by a few burdens.