I’m Sorry for Getting a Head Start but I Decided to Live Everyday Erotically - Chapter 6: Ando Mikoto 2

At age 5, Amon unlocks the unique «Fury» genetics and is what caused his behavior to change.

After living with his grandparents for 11 years he learned to behave. For reasons he can’t know, his grandparents faked their deaths, and now he needed to move.

Now he would have to face a new challenge which was to live with his mother and stepfather and two twin sisters not linked by blood and go to school.

When necromancers perform a great ritual to summon an undead servant, they bring a powerful vampire into their world. And now, their fate is sealed as food, but for Klaus, this is just the beginning of his adventure. In a cruel world where people will do anything for power and immortality, he is already very strong and immortal, so what's left if not start a family and have fun stepping on arrogant people through the way?

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

Oosuki Masato is an ordinary high school boy who is magically transported to an alternative world, but for some reason his doting, over-protective mother comes along as well.