The Promise Sealed with Our Lips - Chapter 45

Before going to college, an ordinary high school student went to celebrate and got drunk. When he woke up, he found himself in a completely different world. There was a big sect, the approaching sect entrance examination, a slum where his body’s previous owner lived, and a shared memory about a missing young girl.

When he got tangled in a fight with a few punks in this different world, he fell off a cliff and miraculously found himself still alive, with two more voices ringing inside his head. They were Sword Master and Saber Master. In the company of them, he continued to find out more about this whole new world. He took the sect entrance examination, entered the sect, met a strange man in black, and even participated in a major competition of the sect to have a chance to win over his peers!
In this whole new world, he was born again and got to explore the fantastic martial world!

- Description from Novelupdates

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

[Warning: Mature content, lemons, comedy, MILFs, NTR, and a villainous protagonist!]_____[Ding! Congratulations, Villain! Your survival chance is 0.01% unless you NTR every hidden boss in this world. Start now or perish!].....James Tanner’s life could be summed up in one word: boring. After barely a week of being a rookie cop, he met his end courtesy of a speeding red sports car.But death wasn’t the end. It was just the beginning.When James woke up, he found himself in Aurendral, inhabiting the body of a rich young master who had spent years blind due to a mysterious condition.Fortunately, the blindness vanished when James merged with the body, leaving him with perfect vision—and one massive headache.[Ding! Issuing First Death Mission: NTR the hidden boss in this region within 90 days… or perish.]What choice did he have? Forced into the role of a scheming villain, James Tanner was about to shatter conventions, steal hearts, and become the strongest and most fearsome seducer this world had ever known.Because if he was going to be a villain, he might as well be the best.[Note: MC takes other guys' women, they don't take his.]

After dying in an oddly anticlimactic vending machine accident, Kazuki Ren is reincarnated in the demon realm—not as a hero, not as a villain, but as the only human male student enrolled at the mysterious Academy of Ruin, a school where all the professors are demon lords and all the students are powerful, beautiful she-demons.Ren is told he has one task: survive.But there’s a catch. The Academy’s darkest secret is about to awaken, and Ren holds a hidden power that could either destroy the demon world... or rule it.Now surrounded by seductive demons with hidden motives, eldritch tomes, forbidden dungeons, and twisted exams, Ren must master his ability—or be consumed.Magic, mystery, danger, and temptation await in this dark academia harem fantasy.