Immortal - Volume 1 Chapter 8

Nagasawa crossed to Naruto Universe and was bound to Konohagakure.

If Konoha is severely damaged and destroyed, Nagasawa’s lifespan will be reduced.

He panicked at the thought of the upcoming Nine-Tailed Demon Fox’s attack , and the thought of Konoha getting destroyed left him in despair.

Fortunately, while bound to Konoha, he can obtain templates of powerful characters.

At the beginning, He got the Whitebeard template! Since it’s the Whitebeard from the Summit War of Marineford, he can use Tremor-Tremor Fruit’s ability and Haki.

Facing the Tailed Beast Ball, which terrorized Konoha Shinobi, Nagasawa leaped and shattered the Tailed Beast Ball with one punch!

- Description from Novelupdates

This story tells the life of two people, a noble only in name and an older wife from the army, married through a tentative agreement. In the bone-chilling cold, they spend their time hunting, gutting, and cooking by the fireplace. Their daily life passes peacefully. This is the warm love story recounting their daily lives.

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.

Four years ago, Kazuma Kannagi was defeated by his cousin Ayano Kannagi for the right to be the successor of Enraiha, a sword passed down in the Kannagi family. His defeat, along with his lack of talent for En-Jutsu, the fire arts, the Kannagi’s specialty, resulted in his banishment from the family. Now, Kazuma returns as Kazuma Yagami, a skilled master of Fū-Jutsu, the wind arts. At the same time, a number of murders at the Kannagi residence perpetrated by a powerful Fū-Jutsushi cast suspicion on him.

Volume 1-6 makes up the main story. Volume 7-12 are various short stories, also known Kaze no Stigma Ignition.

Note: Only v4 epilogue remains untranslated for the main story.