MTL - After Rebirth, I Returned to Miaojiang to Inherit My Family Business - Chapter 229

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.

One day, I woke up only find out that I’d become a Demon Lord, an individual responsible for protecting a dungeon. The world I’d been spirited away to was one filled with violence. Gigantic monsters wandered through it and competed with each other each and every day for the right to survive. I had no choice but to strengthen my dungeon’s defenses in hopes of living another day—or at least that was what I’d thought. For some odd reason, I instead ended up spending my days in relaxation and bliss.

[Hiddenidentity, Femalelead, Loveaftermarriage]She originally planned to take her sister's place and marry a 60-year-old man, but accidentally married him, who was the richest man as he had also made a mistake. She thought they would soon divorce, but he chose to temporarily maintain the marriage.The public disliked her because of her ordinary background and believed that she was not worthy of him. However, her multiple identities were gradually exposed: academician at the National Research Institute, a brilliant doctor, the racing god, national representative of Go, and gold medalist in figure skating. And when the world found out that their marriage was only contracted for one year, she garnered numerous suitors. “Get out! We will never divorce! Never and ever!” he declared.

The gong has loved the shou for a long time already but he does not dare to confess his feelings. Without any better option, he joined forces with a system to kidnap the shou, dragging him through many quick transmigration world in an attempt to capture him. Afterwards…

Shou: This bed partner is very good. Can develop into a long term bed partner.

Gong: Why is it just a bed partner? Let’s agree to love each other!

Ye Jun Ge: Did you take your medicine?

System 004: …QAQ

- Description from Novelupdates