Harem Investment System: Getting Money And Women - Chapter 25: An Unexpected Offer

That lonesome night as he lays dying in the hospital, fearing of death and desiring the taste of life, his mind became unprecedentedly complex with mixed emotions.

Myasthenia gravis — an incurable disease where one’s muscle slowly degenerated until the day when one can no longer move and only tears may flow.

“Is this… dying?”

When he opened his eyes again, he had crossed over into the body of a two months old infant, right in the middle of an assassination attempt.

He was born as the illegitimate son of a noble. His name was Fan Xian; and with that name came the burden of deep political secrets and the legacy of his mother.

He understood; to survive, he needed unparalleled strength, money and political power.

To a new world with the luxury of a new life, so named; Celebrating the Remaining Life.

- Description from Novelupdates

An otaku with a hobby of masturbating was reincarnated as the son of a great mage.

As soon as he was born in this life, he vowed with a goal of embracing women till his death.

That said, when he became 20 years old, the Demon Lord which was sealed by his ancestors revived, and now it is his role to seal it once again.

And that demon lord is sealed in a tower dungeon that is rumored to be impossible to capture.

However, by an unexpected coincidence, he had found out that the Demon Lord is also one of him, a kindred spirit from within,

so he joined her instead and filled several traps in the tower dungeon, and thus they enjoyed a s*x spree with all the women coming over!

One day, Luo Jian woke up from his sleep and found himself in a locked chamber where the door and window were all sealed. A note with a few lines written on it was tacked to the wall: “Escape from this room within an hour, otherwise, you will die.”

There is a sequel called Reincarnation Night (轮回之夜) that takes place in the same universe but has different main characters

- Description from Novelupdates