The supporting character's harem is very normal - Chapter 498: Successful Auction

After switching bodies, Jiang Nan Shu becomes the villainous true daughter in a melodramatic tale and is bound to an all-encompassing revulsion system. If everyone's level of disgust for her reaches 100, she can return to her original world with a prize of ten billion. Being reckless is just one of her many skills. Starting with a disgust level of 89, Jiang Nan Shu sets a modest goal for herself: to live a life collecting easy money within six months. Unbeknownst to her, everyone can hear her inner thoughts!When facing the domineering CEO eldest brother, she says outwardly, “I think this project is excellent and will make a fortune.” Inwardly she thinks, “I hope you don’t go bankrupt! Once you're out, I'll steal your company's secrets.”When dealing with the indifferent medical second brother: outwardly, “The food at your colleagues' gathering looks so appetizing.” Inwardly she thinks, “I'll switch tables when the second brother picks food, to avoid catching any diseases from him.”When facing the sickly research third brother, she says outwardly, “Third brother, you're amazing to conduct such tough experiments, keep going.” Inwardly she thinks, “I’ll gracefully exit before your experiment explodes.”When interacting with the pop star fourth brother: outwardly,“These songs suit you so well, sing them all, and fame is just around the corner.” Inwardly, “Just wait for the news to break about your tax evasion.”When advising the love-struck fifth brother: outwardly, ”She's taking an hour out of her busy schedule to be with you because she loves you.“ Inwardly, ”You’ve been turned into a grassland of green; your goddess has a different companion morning, noon, and night. Bet you didn't see that coming!“As the male protagonist looks at her with increasingly deep eyes, saying, “Let's be together,” Jiang Nan Shu weeps, saying, “Don't let your sister misunderstand, I'm not worthy!” Internally, “Money's hard to earn, crap's hard to swallow, the life of a supporting character matters too!”However... why does she end up as the darling of the whole group in the end?

A scientific genius named Thomas Harrier was transmigrated to an imperial prince body after a car accident that took his life. He found out that he is in a world similar to our own with a timeline akin to early twentieth century. The body that he is occupying was the imperial prince of a failing empire who suddenly rose to power after a successful assassination attempt of his father. Unaware that the attack is just the beginning of what is to come. He faces many challenges throughout. Will Thomas Harrier be able to live his second life in peace while running an empire and getting it back to its former glory? Or will he succumb into a conspiracy lurking within the country's borders?

Expect some:

Cold war era techs.

Super battleship with advanced electronics, propulsion, and fire control systems?
Helicopters?
Missiles?
Modern medicines and equipment?
AC-130?
A nuke?
Challenger or Abrams or Leopard?
F-4 Phantom or MIG-21?
Colored TV's.

Everything!!!

PS. Cover not mine, I just found it on google.

In a world where magic rules and human nations fight to survive, a 14-year-old stowaway finds himself thrust onto the frontlines of war. With no allegiance but to his own cold logic, Lugh is forced to navigate battlefields of steel, sorcery, and shadows. What begins as an escape soon becomes something far greater—whether he wills it or not.Gunmage – When spell and steel collide, a new kind of warrior is born.

One day, Song Shuhang was suddenly added to a chat group with many seniors that suffered from chuuni disease. The people inside the group would call each other ‘Fellow Daoist’ and had all different kinds of titles: Palace Master, Cave Lord, True Monarch, Immortal Master, etc. And even the pet of the founder of the group that had run away from home was called ‘monster dog’. They would talk all day about pill refining, exploring ancient ruins, or share their experience on techniques.

However, after lurking inside the group for a while, he discovered that not all was what it seemed…

- Description from Novelupdates