A Record of a Mortal's Journey to Immortality: Immortal Realm - Chapter 10: Crisis

Xiao Ze, who was dedicated to the people and vowed to become a generation of Ming Jun, accidentally fell on a little lady.
The little lady was born beautiful and lovable.
So Xiao Ze accepted his life and got the name of fear.

ps:
①The male protagonist has no concubine, and he is dedicated to serving the country.

- Description from novelbuddy

After being betrayed by her fiancé and her cousin sister, she accidentally rescued an elegant but indifferent young master. Never did she expect to marry him and surprised many!

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

At the Edge of the Void…A soft blue light hums, pulsing with energy, its robotic voice ringing with purpose.> “Do you accept me, System 0404, the Harem-Building System?”A young man in his twenties, eyes shining with excitement, eagerly responds:> “YES!”The blue light flares—The universe shifts—The binding process begins—DING!> [System Successfully Bound to…]…Daphne Han???????***System: “If you’re going to RUIN the harem-building mission, I’m not helping you!”Daphne: “Okay, I’ll just win without you.”System: “…Wait, what?”***World one:Male Lead: “Why are my offers disappearing?!”Daphne: “Oh? Maybe you just weren’t talented enough.”System: “YOU CAN’T JUST DELETE THE PROTAGONIST!”Actress #1: “Wait, I actually love acting, not this forced romance subplot?”Actress #2: “Oh wow, working under Daphne is way better than chasing ML’s validation.”Male Lead: “WHERE DID MY HAREM GO?!”System: “DON'T RUIN THE PLOT!”Villainess: “What do you want in return for everything?”Daphne: “You.”System: “NOOOO, SHE’S SUPPOSED TO BE HIS FINAL LOVE INTEREST!”World two:Emperor: “You were supposed to compete for my favor!”Daphne: “Nah. I’m the one with favor now.”Heroine: “Can I join your court instead?”System: “THAT'S NOT HOW HAREM DRAMAS WORK!”***CEO: “I was supposed to be her fate!”Demon Lord: “SHE WAS SUPPOSED TO REDEEM ME!”Imperial Prince: “What do you MEAN she’s not interested in me anymore?!”System: “THIS IS NOT HOW THESE STORIES WORK.”