Machina Arcanis: Two Worlds Collided - Chapter 6: Treasure Room II

Entering Tokyo in the bubble era, in this strange era, the only familiar ones are Matsuda Seiko, Nakamori Akina, Kudo Shizuka…

- Description from novelbuddy

In a land where no magic is present. A land where the strong make the rules and the weak have to obey. A land filled with alluring treasures and beauty, yet also filled with unforeseen danger. Three years ago, Xiao Yan, who had shown talents none had seen in decades, suddenly lost everything. His powers, his reputation, and his promise to his mother. What sorcery has caused him to lose all of his powers? And why has his fiancee suddenly shown up?

In a future timeline, the earth was visited by a species known as the Slarkovs.
Having lost their home planet and in search of a new one, earth was the next habitable planet for them.

Humans and Slarkovs made a deal with each other in return for the Slarkovs living on earth.
The Slarkovs traded their technology and knowledge for a new home.
They were similar to humans except for some of them who had slight differences so fitting into the society wasn't a problem.
Over the years Slarkovs and humans began to mate with one another and reproduce offsprings.
This in turn created a new species known as the mixed-blood.
Centuries later mixedbloods could tap into their bloodline and perform unimaginable feats.

Gustav born into an age where bloodline determines everything, struggles to fit with a useless bloodline.
His bloodline only grants him the ability to change his hair color, destroying his hopes and dreams for a great future.
His fate is turned around when an unexpected situation leads to him finding a system that grants him the power to unlock and upgrade bloodlines by completing quests but he's baffled by two quests with a five-year deadline. Success will grant him unimaginable rewards...
But only one thing awaits him if he fails... Death!

Follow Gustav on his interesting journey filled with unprecedented adventures, danger and death, maybe?

[Warning: This story contains extreme violence, philosophical depth, psychological breakdowns, self-improvement, self-realization, and themes of maturity.]“Even Gods need character development.”That was the belief Pratham lived by—struggling, always pushing forward. Until the day he died, starving in a world too cruel to care.But death was only the beginning.He transmigrates and awakens in a multiverse as Leon. In this multiverse, the greatest threat to humanity isn’t demons or beasts, but Entities. In response, civilizations across each universe forged a single hope: the Entity Hunters Organization, training warriors to stand against the impossible.He had no magic. Just his will, his fists—and a little sister he swore to protect at all costs.Enrolling in the Entity Hunters High School, Leon finds comrades, purpose, and war. He fights beside them across different planets and universes, grows with them, laughs with them—then loses them all.Leon rises not as a hero, but something else.