My Beloved Dog is the Strongest in Another World - Chapter 1109

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.

The protagonist transmigrates into a novel and gains a system where they grow stronger by simply writing in a diary.July 7th, sunny: “The boss’s outfit is hideous again. Wouldn’t it be better to wear something cooler?”July 7th, evening: “I’m about to have my engagement called off. So excited! How should I act?”July 7th, evening: “Lin Qingyue, the female lead, is probably going to drown her sorrows in alcohol.”The protagonist thought it would be easy—just jot down daily musings, record life’s events, and earn rewards. All while playing the part of a villainous, bootlicking second-generation rich kid, moving along with the original plot.But unexpectedly, the female leads gain access to copies of the diary entries.One by one, they stop following the script, and the plot spirals completely out of control.July 10th: “The female boss is an idiot—no one would want her.”Soon after, the protagonist gets punished at work, all because they entered the office with their left foot first.

“What’s my class?”[Beast Tamer – Class E]“..Seriously?”Lee Min-Jae was a workaholic with no social life who died slumped over his keyboard. When he opened his eyes, he was in an RPG-like world — but with the worst class imaginable: Tamer.Tamers were seen as useless. Weak. Limited to disloyal, expensive-to-keep wild monsters.But he wasn’t just any fool. He was a systems-obsessed gamer, an expert at finding exploits and shortcuts.With his cold, analytical mind, he chose to break the game’s rules — by leveraging the most reviled mechanic of all: contracts.Where others saw abomination, he saw an exploit. And he was ready to turn the worst class into something unbeatable.---------------This story have:[Adventure][Smut][MSmut] (no NTR).[Harem][System / LitRPG][Strategy] - cold planning, exploiting mechanics, creative use of abilities.[Cold and Calculating Protagonist] – no naive romance.[Worldbuildin] – rules, politics, economy.[No NTR] – the protagonist is not betrayed, no passive humiliation content.

Twenty years ago, she was taken in as the Lin family’s young heiress through a twist of fate. But mistakes would eventually be corrected one day. When the real daughter of the family returned and her foster parents begged her to stay, she obliged. Unbeknownst to her, this was actually a scheme disguised as familial affection. They only kept her around to squeeze her dry of all her value!