Ryuu Kusari no Ori -Kokoro no Uchi no “Kokoro”- - Regarding Vol.4 LN

However, he did not know that he was not raising just a harmless pet, but a biological weapon secretly made by the government… a real monster.

As a former librarian, Rand felt that he had been living an ordinary life, the one that he had reclaimed unconsciously every single day.

Recently, he has been a little upset because the pet fish he accidently brought home to raised seems to have undergo some strange changes

Well, it turned into a merman.

- Description from Novelupdates

Ding!『You have acquired the skill: [Universal Language] – All tongues shall now bend to your understanding.』『You have acquired the skill: [Dimensional Exchange] 』『Item Detected: [Gold Coin x50] 』Initiating Currency Exchange…Exchange Rate: 1 Gold Coin = $1,000 USDConverting [50 Gold Coins] → [$50,000 USD].....Kael Lancaster grew up believing his family was ordinary—until he discovered that his estranged grandfather, Theodore, was a multi billionaire.Struggling with his family's debts and uncertain future, Kael decides to approach his grandfather and move into the Lancaster estate, becoming the old man's caretaker. For two years, he endures the family's contempt and Theodore's cold indifference, clinging to the hope that his loyalty will one day be rewarded.But when Theodore dies, the will delivers a brutal blow: Kael inherits nothing.Or so it seems.However, His grandfather had left him something else.A portal through which he could travel to another world—Kael can trade between worlds, amassing power beyond imagination.

The notorious imperial court lackey and the meritorious military general were well-known for their mutual dislike, a pair of arch-enemies set in stone. Who could have foreseen the unexpected change in the winds of heaven: the general injured on the battlefield, both legs disabled, and even forced by the emperor to marry his nemesis.  

With one marriage edict, two people with mutual hostility are forced to marry and live under the same roof. Yet after these long days together, they come to the realization that this fellow is not truly devoid of any saving grace/unattainable and high out of reach.

- Description from Novelupdates

'Death' It was meant to be the end, but it brought a new start.After a destructive nether storm consumes his world, Jack finds himself face-to-face with a powerful being who tasks him with a mission he can’t refuse.Reincarnated as Asriel—the most tragic, doomed character from a novel he once read—Jack’s frustration grows: “Damn it, why this fool?”Now, he must navigate Asriel's cursed life, facing relentless supernatural beings that threats him with a single hope:[Necromancy System Activated!][Ascend as the Ruler of the Undead!]But can Jack rise above Asriel's fate, or will he, too, fall prey to the shadows lurking in his new world?