Song of Adolescence - Chapter 443 Exorcise Demons and Subdue Evil Fiends

I reincarnated as Luna, a supporting character who is accused of ruining the heroine and hero’s relationship, and is mu*dered. I’m not interested in someone else’s man, but the heroine’s friends bully me every day. “Why are you trying to get close to someone who’s already taken?” “That’s right, please stop! Why are you doing this?” “Stop doing such terrible things!” So Luna decides to announce it in front of everyone. “I don’t want someone like Fersen even if you beg me to take him so stop bothering me. I’d rather date Anthes Vincent, who’s rumored to be insane.” And soon she meets someone who she never expected to meet…… “I heard you have an interest in me? The truth is, I do too. Is it a coincidence?”

Transmigrating into a poor and mistreated young lady's body, what will the craziest alchemist of the seven realms now do?

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.

I am a holy knight. To be precise, I am the Church of the God of Light’s Sun Knight…in training.

The Church of the God of Light worships and serves the God of Light, and theirs is one of the three largest religions on this continent.

As the whole continent knows, the Church of the God of Light has the Twelve Holy Knights, and each one has his own unique personality and features.

To be the Sun Knight is to have shining golden hair, sky blue eyes, a compassionate nature, and a brilliant smile.

…even the Sun Knight-in-training is no exception.

The 38th generation of the Twelve Holy Knights have completed their term of office, yet the time for the 39th generation to take over is still far in the indefinite future.

The Judgment Knight is brash and easily angered; the Storm Knight and the Leaf Knight are always fighting nonstop, day and night.

Since childhood, the Sun Knight-in-training has watched the others grow from kids into adolescents.

What must he do in order to become comrades, who will fight through thick and thin for each other, with this group of “younger brothers”?

“Benevolent God of Light, may I ask when I will complete my training that has taken more than ten years?”