Toaru Majutsu no Index - Volume 12, Chapter 3: Misaka and Misaka’s younger sister. Sister_and_Sisters.

When I woke up, I had been reborn as a baby. My mother passed away and I was neglected by my father. Even though I was born in a Marquis family, my life started on a HARD MODE. But I won’t be discouraged. I will eat well, sleep well, move much, get whatever I can get and live happily.

An unnamed 34-year-old Japanese NEET is evicted from his home following his parents' death.

Upon some self-introspection, he concludes that his life was ultimately pointless.

Walking down a street he intercepts a speeding truck heading towards a group of teenagers, in an attempt to do something meaningful for once in his life he manages to pull one of them out of harm's way before getting himself in the way of the truck and dying.

Awakening in a baby's body, he realizes he has been reincarnated in a world of sword and sorcery.

He resolves to become successful in his new life, discarding his past identity for his new life as Rudeus Greyrat.

With his engagement at hand, the most terrifying and legendary person of the legal world, Fu Huai’an, returns with a son.

Before the engagement…

He asks, “Since you love Wen Moshen, why are you in my bed?”
She says, “Because I cannot watch idly as Wen Moshen’s woman enters an engagement with you.”

With a cigarette in Fu Huai’an’s mouth, he crosses his legs. Across the light cloud of smoke, he squints his eyes—watching as Lin Nuan’s slim arms wrap around his neck; he feels stirred.

So a person can love another so passionately.

“You call what you did a kiss?”
“…”
“What a pure lady!”

Fu Huai’an spews out a cloud of smoke and snuffs out the cigarette. With a mellow voice, he says, “Let me teach you what kissing is!”

But, what he teaches Lin Nuan doesn’t seem to be only a kiss…

- Description from Novelupdates

[By the Author that brought you “Return of the Frozen Player”!]The Return of the Fallen Tower Master: The Revival Era of the Magic Tower