MTL - Yu-Gi-Oh!: Underworld Boss, Cancerous Creator God - Chapter 55

The black dragon that rose from the depths of the South Sea unleashed an apocalyptic tsunami... Flame demons destroyed city after city made of steel and concrete, calmly departing from the center of nuclear explosions... Alien gods attempted to rule the entire galaxy...This is a future world where human technology is highly advanced.It is also an era that sparked a frenzy of Life Evolution in the Martial Path.Li Yuan, a Martial Path student on the verge of taking his college entrance exams, struggled to advance in this world while harboring the peculiar Divine Palace capable of envisioning the galaxy.Years later.“My current flying speed is 122,682 meters per second, and my power burst is...” Li Yuan flew at extreme speeds through the atmosphere about 180 kilometers above the surface of Blue Star, his cold eyes fixed on the massive creature at the dark void's edge, resembling the mythological dragon: “You, must be the strongest among all the invading Demigod life forms.”“It's just unfortunate that I can now be called... Martial God!”

Another entry in what you can call the Proto Harem Series: the books written before the Harem Series that take place in the same world.

It’s about a swordswoman whose student is captured, so she goes to rescue her.

Cale Virel was just a normal office worker.He was bored and tired of his life, waiting for it to end.And then—Bam!One night, two robbers targeted him!And instead of surrendering, he fought back!Though, in the middle of doing so—PHUCK!He got stabbed and died...He didn't regret it though.After all, he's not really afraid of death anymore.And so...He rested in peace..........Or so he thought!Cale Virel—“Huh? What the fuck?”He woke up as a young slave named Kaiser in a different world!And given another life he didn't ask for again—“Fuck this shit!”Cale, or should I say—Kaiser—“Ugh, whatever.”Decided to live it... By just doing whatever he feels like until he dies.