The Devil's Sleeping Beauty - Chapter 150 Darling, you should put your gun away

Due to an unexpected turn of events, Xia Fei consumed a Super Gene Optimization Fluid that bore no brand, expiry date, instructions or stated its place of origin.
Our story begins here…

Ruins stretched across the landscape in the apocalypse after the nuclear war.

One day, I woke up only find out that I’d become a Demon Lord, an individual responsible for protecting a dungeon. The world I’d been spirited away to was one filled with violence. Gigantic monsters wandered through it and competed with each other each and every day for the right to survive. I had no choice but to strengthen my dungeon’s defenses in hopes of living another day—or at least that was what I’d thought. For some odd reason, I instead ended up spending my days in relaxation and bliss.

In the world of Norse mythology, a human boy falls in love with Waltraute, the fourth Valkyrie sister. He wishes to marry her, but Waltraute gives him an impossible challenge to deter him.

Nevertheless, the boy is determined to carry out the dangerous task and to marry Waltraute afterwards.