Apocalypse: I'm the Landlady of the Refuge - Chapter 48 - Space Elimination Game

He rose from abjection and achieved eternity in glory.
He embraced the prettiest beauties and killed the strongest opponents.
He was able to shift the clouds into rain and cover the sky with one hand.
He could overrun the entire world and go anywhere as he pleased.
He pacified wars and held the world in awe.
He was matchless in the world.
However, his hair turned white overnight for his beloved woman and he was on the verge of death.
He was surrounded by enemies who were trying to take his life.
He struggled his way to become mighty and fought for everything he cherished.
For this age, he was the only king of the Dark World.
His name was a byword for might.
As a man living in the world, his only ideal was to pursue brilliance.

- Description from Novelupdates

When The Cute Kunoichis Spied on Their Teacher's Secret is a light novel written by Kazuma Kamachi and illustrated by Ryuushi Tajima.

The story takes place in a world where Japan never ended their isolationist phase, and agents from foreign powers are always threatening to steal the country's advanced technology. In order to combat this threat there has been a resurgence of ninjas that use Strategic Martial Arts, techniques that combine cutting-edge modern technology with a traditional foundation of martial arts and ninjutsu. The story follows Souha Sugiyado, a 17-year old ninja instructor and former ninja prodigy who was forced to retire from active duty by the wounds he suffered in his last mission. Souha's four students are all kunoichi who have all gained the rank of Elite Ninja, the highest official rank available to ninja. However, one day two Shogunate ninja approach him with the news that his four students have gone rogue and have stolen a portable modular nuclear reactor, and thus they ask for his help in bringing his students to justice.

Third Miss Luo relies on her father’s power to create chaos everywhere and is notorious for bullying the weak. When she had nothing to do, she led a group of servants to the streets to flirt with beautiful and handsome boys. For Princess Qingyang, if this kind of person dared to behave wildly in front of her, she would just kill her with a single finger—until she opened her eyes again and found that she became Third Miss Luo, Luo Sheng.

- Description from Novelupdates

Yuder was a commoner Omega who rose to the top with his ability.

When he woke up again after being falsely accused and executed, he was back 11 years ago before everything began.

A chance to get back……

He must not repeat the same mistake he did before.

To survive, and to save the world, now he had to save the man he had killed!