Let’s Divorce As Agreed - Chapter 1

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?

"Marry me. Once we're married, I will be loyal to you for life—as long as you keep me alive." Qiao Jiusheng was pushed into the water by her older twin sister, had her identity stolen, losing her old love and life. With no other choice, she seeks out Fang Yusheng, the blind man rumored to have no interest in women. With blank and empty eyes, he says, "Sure." In her past life, she was betrayed by her sister and trapped in the basement. Her tongue was cut off as she watched her sister take her place, winning overall her loved ones, marrying her lover of six years, and starting a family with him. Now that she's back to a time before it all went wrong, Qiao Jiusheng escapes from the river and goes to her boyfriend's older half-brother. She puts on a mask and marries him, to fight their common enemy. The wheels of fate begin to spin, and the severed threads of destiny are once again entwined... Before their wedding, he tells her, "Don't peek at me so openly just because I'm blind and can't see you." On the night of their wedding, he tells her," You don't have to dress like a bear. I don't care for women." Half a year after their wedding, just because she gives another man another look, Fang Yusheng covers her laptop, phone, bedside drawers, desk, and wallet with nothing but his selfies.

Based on the popular Vocaloid series, by HoneyWorks, called “Kokuhoku Yokou Renshuu (Confession Rehearsal)“:

Natsuki, a third-year at Sakuragaoka High School, who holds unrequited feelings for her childhood friend, Yuu, who’s in the Film Club. However, instead of being honest about her feelings, she makes him be her confession “rehearsal” partner. Unable to say her true feelings, things start to get complicated when Miou and Akari, who are also in the Art Club, get involved! Will she ever be able to confess for real!?

Once I’ve become Immortal, then my attempt to conquer the world shall begin.