Blackstone Code - Chapter 191:

Su Yuzhou reincarnated into the ABO world after his death and became a top-level alpha. Influenced by the conceptions of his previous life, he never thought that a susceptible period would have any effect on him – after all, as an upright young man, how could he be enticed by pheromones to push down a weak Omega?

Then, he became the one who was pushed down _(:з”∠)_

Atypical ABO story, Omega Gong X Alpha Shou.

- 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

Office worker Leon is reincarnated into a particularly punishing dating sim video game, where women reign supreme and only beautiful men have a seat at the table. But Leon has a secret weapon: he remembers everything from his past life, which includes a complete playthrough of the very game in which he is now trapped. Watch Leon spark a revolution to change this new world in order to fulfill his ultimate desire…of living a quiet, easy life in the countryside!