From Abyssal Invasion to Bursting Stars with a Single Sword - Chapter 947 - 546: Metal Planet, Mechanical Demon

Each stroke of good luck is a triumph over someone else’s misfortune.Jack Grim, the son of two legendary assassins, was born and raised on nothing but coldness, and the skills to spill blood.At seventeen, Jack received his final task as an assassin apprentice under his parents.“Succeed, and you’ll run your own organization — live the life you’ve always dreamed of.”For Jack, it was everything he had ever wanted: the chance to finally become the professional assassin he was born to be.He struck his target at midnight, succeeded, and received everything his parents had promised.But in the wake of victory came a pounding headache, a relentless fever—and then… transmigration.Jack now found himself in Raiden’s body, the keeper of the Book of Ashes, the heart of the Devourer, and the very book the coward Raiden had died protecting with his life.Jack had no desire to live in another world, magic or not. He simply wanted to return to his life as an assassin.But duty had other plans. The balance of this world now rested on his ability to protect the book, and like it or not, the responsibility was his to bear.

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

The protagonist, having degenerated into a “loser” after being unable to find employment, gets caught up in someone else’s attempt to commit suicide-by-train and ends up traveling to another world. The numerous cheat powers he demands from God are all granted to him. But contrary to expectations, these powers bring about disastrous consequences for the protagonist.

Having reincarnated into another world, the optimistic protagonist (Yuuri) starts his(her) heart-warming training days with his(her) teacher.

By the time I reached thirty, I hadn't managed to provide any of the happiness I wanted for my wife.I also still couldn't become the support my parents relied on.At this turning point in my fate, my income suddenly began to increase randomly.(A daily life tale in a wealthy family setting, featuring a single female lead and no harem.)