Avoid Yandere Constellation - Chapter 148:

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.

Ye Family goes bankrupt, and her fiancé's family watches coldly.Ye Li signs a contract and marries her fiancé's uncle in a flash marriage.After marriage, Ye Li is determined to repay the debt of one hundred million with interest, hoping to give Fu Yanci freedom so he can be with his true love.When it reaches 5 million, Fu Yanci gets upset.At 50 million, Fu Yanci leaves home for three days.When finally paying off the full one hundred million, Ye Li is cornered by the man: 'Divorce, huh? Sure!!! The family property is yours, and so am I! I'll follow you everywhere!'Ye Li: ......

Gu Qingmo began to disguise herself as a man because of a word from her master.

Later, because of the words of my brother, I tried not to open my mouth if I could.

Later, I don’t know why the whole cultivation world is talking about the old master of Wanjianzong, the closed disciple of Xiaoyao Sanren, who is cold-hearted, taciturn, self-restrained and respectful, and who cultivates the ruthless way.

Mo Chuli thought so until she died in her hands.

However, since he was reborn and accepted as a disciple by Gu Qingmo, he discovered that——

Well said, cold hearted! taciturn! Self-denial!

It’s all an illusion!

Small snippet:

The day before Gu Qingmo was going to take Mo Chuli out for a training session, the headmaster made a special trip to Jianfeng and said to Mo Chuli, “Chuli, my uncle told you that if your master wants to go out in the future, you will definitely to follow.”

Mo Chuli: “Sect Master, why is this?”

Liu Qingbai: “Your master’s words are easy to offend people, so you have to keep an eye on it.”

Mo Chuli: “…”

[Woman pretending to be a man to decorate the real world’s first upright and paralyzed heroine × Seizing the house after her death was accepted by the heroine as an apprentice and the former Demon Lord hero]

ps: The female protagonist has a ceiling level of combat power, and the male protagonist is a growth type

- Description from novelbuddy

In the far future humanity is threatened by monstrous beings called kaiju now humans have expanded across the galaxy with the development of new techniques and fleets of mechs.Alto a young boy with dreams of becoming a great mech pilot is forced to be a mech designer. He finds a strange technology that opens his eyes to the vast secrets of the galaxy, now with a new purpose Alto must become something the world has never seen before.A/N: Just wanna do a good sci-fi book