MTL - Transmigrated as a Rich and Vicious Widow - Chapter 122 extramarital marriage

An ordinary medical student suddenly got the blessing of the system and could directly see the patient’s health! Since then, treating illnesses and saving lives has become commonplace, and he has also become a legend in the medical field.

- Description from novelbuddy

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?

After successfully completing the tasks of the B-Class World, Lu Yue finally succeeded in entering the A-Class world.

What? The blackening value of the males in the A-class world is above 80!!

Lu Yue: What are you afraid of? Calm down!

This is a story of a drama king and a black-bellied male.

First World: Mafia’s Pet Lover
Second World: Revenge of the Reborn Boyfriend
Third World: Emperor is a Ladies’ Man…

- Description from Novelupdates

A spin-off of Lillia and Treize, Meg and Seron is a high school adventure/mystery/romance/comedy of sorts taking place in the rough equivalent of the 1950s. The story follows Seron, a stoic and handsome bookworm who is in love with his classmate–a sweet, oblivious transfer student named Meg.

Meg and Seron takes place at around the same time as Lillia and Treize, but knowledge of the main series is not necessary to read Meg and Seron.