Kami-sama no Memochou - Volume 9, Chapter 7

“Stripped of his power, betrayed by those he trusted, and abandoned by fate itself, the young master of the Celestial Clan faces a choice: cling to the tattered remnants of his righteous path or to embrace the darkness blooming within. When a catastrophic fall strips him of everything, he, along with his fiancée by his side, abandons the righteous path. Witness the birth of an anti-protagonist couple, as they forge contracts with ancient, terrifying beasts and carve a new destiny from the bones of their enemies.”In the heart of the Azure Star Continent lies the legendary Celestial Clan, rulers of an unbroken legacy of power, wealth, and influence. At its helm stands Xian Tianyang, a prodigy born with unparalleled talent and destined to inherit the mantle of leadership. Calm, calculating, and relentless, Tianyang has forged a reputation as an unshakable force, a young master whose genius is rivaled only by his ambition.But the path to supremacy is fraught with danger. In a continent where alliances shift like desert sands and rival factions sharpen their blades, Tianyang must navigate a world of intrigue and betrayal. When his childhood fiancée, Lin Yuqing, the “Blooming Empress” of the Eternal Bloom Clan, enters his life, their union threatens to spark both alliances and rivalries that could reshape the continent.With ancient secrets lurking in the shadows, enemies plotting from every corner, and the weight of his family’s legacy on his shoulders, Tianyang must prove that he is more than just a prodigy—he is the heir to the Celestial Throne.Will their fates intertwine as destined rulers, or will the fires of ambition and duty tear them apart? Prepare for a tale of genius, power, and forbidden emotions, where every choice has the power to change the fate of nations.

In a world teeming with Titans, Colossals, Gigantic Monsters and Kaiju's, Erian who reincarnated makes his living collecting scraps of low-grade Defective Genetic Serum, realised he transmigrated along with his system.

Follow Erian as he grows to become the strongest Disaster Grade Titan with the help of his Titan System!

The most vulnerable time in a tennis game is when you are leading; even if there is a match point, the game is still possible.

Football is round, tennis is also round.

- Description from novelbuddy

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.