Dungeon Overlord: Monster Girl Harem! - Chapter 142: Echoes in the Heart

Igor had asked him to die for the world. She would ask him to die for her. Problem was, he didn't really like dying, not for a second time, at least.

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?

I possessed a minor character who marries the prince. I’m not thrilled about it. The prince is a scumbag who flirts with the heroine despite being engaged and eventually gets defeated by the original male lead. In the epilogue, all he does is apologize to his fiancée and marry her, with barely a line to his name. Well, his personality is twisted, but at least he’s handsome. And since he’s the third prince, he doesn’t have to shoulder the burden of ruling the kingdom. That’s decent husband material, I suppose. Go ahead, make a fool of yourself. You’re going to marry me anyway. I’ll just sit back and enjoy watching your embarrassing history unfold. “Doris Redfield. Don’t expect me to ask you to dance at this ball. Maybe not at the next one either. Or the one after that.” “Yes, Your Highness. As you wish.” “Even though we’re engaged… wait, what?” “It’s just a joke proposal our parents once tossed around, isn’t it? You don’t need to take it seriously, Your Highness. I’m really fine with it.” “…Is that so? Yes, that’s… fine, right?” Why are you panicking, prince? You started spouting nonsense first. Where’s your conscience? But then, this guy really has the audacity to ask something outrageous. “…Do you, perhaps, have another man?” The guy who flirted with the original heroine is saying this now? Calm down. He’ll regret this later. All I need to do is remain a devoted fiancée until then. “What are you talking about? A woman like me… plain, not beautiful, with a gloomy personality, what man would even—” “What? Who dared to say that about you?” …You did, in the original story. This guy is acting weird. But he’s not the only problem. “My dear little sister Doris, that dress you’re wearing today is dreadful. No wonder there are rumors His Highness has abandoned you.” “Well, it can’t be helped. His Highness is too good for me anyway.” “…Hold on. Too good? Who said that? Wait, were you really dumped?” The original villainess, who also happens to be my older sister, Natalie, is suddenly interested in my love life. Why are all the original tr*shy characters growling at each other over me now?!

As a successful villainous BOSS, in addition to having ideas and aspirations, one must also keep in mind three points:First, grow sneakily, don't act rashly (once a villain acts rashly, they basically won't survive past three chapters).Second, you're not a good person, so be ruthless (becoming more evil will make you three times stronger, while redemption weakens you by seven times).Third, remember the two points above. The moment you forget them, your end is probably on its way.