Contract marriage: His Sweet Wife and Cutest Twin Babies - Chapter 1476

While reading a book, a sparkle of light disappeared. And, as it did, a message appeared.

The Immortal Path led to Longevity and Sovereign was heading in ease. When the Longevity was no longer in ease, all living beings were just prisoners. Conspiracy, internal strife, and the invasion of the others, all of it emerged together. 

In such a world, there was such a young man. He made his way upstream, stepping on blood, defying the emperor, destroying the various kings, and slaughtering his way through the hundred clans to form an Immortal Path towards the throne of Sovereign! The Immortal Path was endless, while the Sovereign was limited. He used his blood to forge his immortal legend.

- Description from Novelupdates

I met the male lead in prison.

Damien Rothschild, an immortal who has lived life to the fullest for the past four hundred years, is visited by a mysterious woman who reveals the many depravities of his mischievous brother in another world.To save his brother, Damien must first travel to this other realm. However, the path becomes treacherous as he is tricked and loses everything he once had. Now, he must navigate this new world in search of his brother.This story follows a man who was granted the gift of immortality, allowing him to rise to the very pinnacle of the human race—until he was stripped of everything he held dear in a desperate attempt to save the only thing he ever truly loved.