MTL - Yu-Gi-Oh!: Underworld Boss, Cancerous Creator God - Chapter 334

Xue Xi is forced to fall in love at first sight with this dangerous man on their first meeting. With death being the only other option, she makes the first move:

When gods gather, lightning will strike and the earth will move. Immortals! Which of the numerous way to immortality should one follow? Immortals are hard to seek, but why should immortals hide? Heaven has no mercy, but humans have emotions, and these emotions hinder the road to longevity!

Meet Sora and Shiro, a brother and sister who are loser shut-ins by normal standards. But these siblings don’t play by the rules of the “crappy game” that is average society. In the world of gaming, this genius pair reigns supreme, their invincible avatar so famous that it’s the stuff of urban legend. So when a young boy calling himself God summons the siblings to a fantastic alternate world where war is forbidden and all conflicts–even those involving national borders–are decided by the outcome of games, Sora and Shiro have pretty much hit the jackpot. But they soon learn that in this world, humanity, cornered and outnumbered by other species, survives within the confines of one city. Will Sora and Shiro, two failures at life, turn out to be the saviors of mankind? Let the games begin…

Three years ago, the animals and plants on Earth underwent crazy and unexplainable changes that included transformations, reversions, and the addition of otherworldly species. And it was the start of a brand-new type of profession in the new generation of humanity – Monster Trainers, people who specialized in taming monsters.