MTL - The Empress’s Gigolo - ~ Be sure to look at this

A biker tries to save a cat on the highway and gets hit by a truck (Truck-Kun), he was rushed to the hospital but, due to internal bleeding, he dies only to be reborn as a cat, in a new world with a system.

In this new and vast world, he tries his best to get used to his new body and get stronger along the way. With his overpowered system and skills. To one day become untouchable.

The Age of Celestials has arrived.

In the world where Vincent was sent into, the existence of Celestial Beings greatly stimulated the advancement of humanity. With their help, the humans started breaking out of their shackles as they exceeded the limitations of their mortal bodies.

They have passed down mana cultivation techniques and various combat arts increasing their strength as they fought against the true enemies of the world…

However, as Vincent was sent by his grandfather to complete a very unusual mission, he learned that these majestic Celestial Beings weren’t gods or existences out of his reach… They were actually tools or weapons that humans have been using for their own greed. More than that, he discovered the true origin of the Celestials!

Hence, with the help of his System, he mounted a rebellion…

For those who fought in war, war never ends.

But Xiao Yuan’s war has just begun…a war that has ended.

Guderian?

Rommel?

Manstein?

The USSR needs only one soldier… Shulka

- Description from novelbuddy

300 years after becoming a Demon King, the war angel Ansel faced a serious problem during a certain expedition.

——His halo grew out once again.

Ansel picked an auspicious place that was definitely and absolutely unmanned, and while cursing, he simply and skillfully broke off the newly emerged angelic aperture.

This thing was growing out faster and faster!

When will his undercover mission end already?!

The demon realm was divided and ruled by three kings. Demon King Saros was forced to go on an expedition with his sworn enemy, Ansel.

One day, he noticed Ansel sneaking away from everyone.

Saros decisively followed him, and was shocked to find that his sworn enemy, another demon king of the demon realm, took off a horn headband and fake bat wings. As Ansel cursed up and down, Saros watched as he skillfully removed a cute halo from his head.

This irritable, easily angered guy who loves fighting; the type that was cute when he shuts up but could make even demons angered to the point of ascending to heaven the moment he opens his mouth…

..was actually an angel???

- Description from Novelupdates