Dragoon - Dragoon 64: The Dragon Idiot and the Game Idiot

A man who had emerged from the world’s most secure prison—God of Death Island, known as a super-powered being called the God of Death, had grown tired of the bloody storms abroad and now, like a hidden dragon, he had returned! But due to an accident, he became the contract husband of a beautiful CEO! From then on, he ruled the city, crushed the petty and wicked, and embarked on the tyrannical journey of an urban legend!

A modern-day antihero, who was infamous for his devious acts, dies in an explosion meant to take down a powerful criminal syndicate. Waking up in a world of sword and sorcery, he finds himself possessing a fragile, powerless body with a strange “System” that seems broken. Initially thinking he's doomed, he learns that by pretending to be weak, he can manipulate others into revealing their secrets, granting him abilities they possess. As he rises in power, he discovers that the System was intentionally sabotaged—by none other than his own future self.

He was very happy to be reborn, but why was he sixteen again, he can’t bear to look back at that time.

Why does he return to being sixteen years old, yet still meet Doomsday?

It’s alright to encounter the end of the world, so why did he have to fall in love with someone?

Even if he falls in love with another person, why did it have to be a man?

Falling in love with a man is also alright, so why did it need to be a secret one-sided love?

Even a secret and unrequited love is alright, so why is that man his….

- Description from Novelupdates

I met the male lead in prison.