A Mistaken Marriage Match: Record of Washed Grievances - Chapter 79

In a world where the strong prey on the weak and nobles slaughter commoners like insects, Alex was just a weak boy who lost everything to the cruelty of fate.For the sake of revenge, he rose from the ashes, determined to carve his path through a world soaked in blood and betrayal.But there is something the world does not know—something even Alex himself has yet to discover...A power buried deep within his blood, ancient and untamed, waiting to awaken.

Crossing to One Piece world, he became Roger’s younger brother.

Unexpectedly, Gol-D-Roger who was in his fifties had a teenage brother. But he was so weak.

Fortunately, at the age of sixteen, he actually found himself with a possession soul system.

He had attached to the master IP man, also to the White Phoenix and to Ge Nie with his strong ability of the Hundred Step Flying Sword.

If you think that he can only Purchase these? Then you’re wrong!

Pain, Itachi, Ichigo Kurosaki, as long as there is money, any soul can be Purchased.

- Description from Novelupdates

This is a world where science and magic coexist.

Some people here seek powerful magic, and some seek eternal truth.

A science tyrant who came from another world, started as a little librarian, with magic in his left hand and truth in his right, kicking the door of the new century with one kick.

Some people call him the forerunner of magic, some say he is the founder of science.

Some people describe him that way.

In the new century, Blair is a symbol of evil.

- Description from novelbuddy

Jacob Steve, an Old Man, died at 116 after living a whole life.

But Jacob always had a dark side, which he always suppressed and hid from others.
However, in the later years of his life, when death was inevitable, he understood there wasn't any point in having wealth, knowledge, or desires if you couldn't have a life to enjoy them.

He became obsessed with fabled immortality and devoted his reaming life to extending his fleeting lifespan, but just like any other failed.

However, he mysteriously got another chance at life and found a way that led to fabled immortality.
But he was also forewarned that the way led to it was filled with blood and darkness!

In the end, Jacob chose it anyway with no way of going back, and it was also the start of his suffering and his icky, brutal journey toward the 'Immortality' he wanted so badly!