MTL - WARNING! Tsundere President - Chapter 1046 1046, that must be his daughter! He has been missing for 18 years of little lovers!

Shuu is a member of the literary club that can’t write. One day, he gets a mysterious message on his phone from a girl called Eina, and from that impulsive contact, they begin to exchange messages. They talk of things like their shared interest in novels and grow close. However, when they try and meet, they discover a shocking truth. Eina lives… not in the present, but five years in the past! How will their love develop, parted by five years of nights…!?

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.

Sulí woke up from chaos without any memories, and without a system on her, simply living through each life cycle indifferently, guided by some mysterious force. Slowly, she realized that in every life, her identity was that of a supporting character with a bad ending...A wife discarded by her husband,The leading student led astray,An ordinary girl taken down by vanity,A childhood friend with toxic tendencies,Romances entangled with embroidered balls,The so-called phoenix men...After countless lifecycles, amassing immense merit and golden radiance, Sulí found out that things were far from being as simple as she thought.