KING OF RUIN - Chapter 1: The Return of Kol Vaelros

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.

Shen Yuqing and the Emperor had a secret arrangement––

She was his pampered consort, and she would hit wherever the Emperor directed her to strike;

The Emperor “loved and favored her forever”, and she could do whatever she wanted.

Later, she set her eyes on the Empress who had the same type of marriage only in name…

- Description from Novelupdates

The Ye family’s foolish girl is reborn one day!With an omnipotent divine cauldron and a spiritual space in hand, she is no longer the good-for-nothing, abandoned girl that everyone bullies at sight!She is so invincible with both medicine and poison that even a divine doctor will be nothing beside her, Spiritual beasts beg her to make contracts… Oops, excuse her, even the Beast God calls her Boss.When her scumbag father dares to abandon his wife and daughter, she wrecks and destroys his family.When people dare to bully or humiliate her, she would return that favor a hundred times greater.Reincarnated as a human once more, she returns like a powerful sovereign. However, she never expects to be involved with the devilish and bloodthirsty him.Originally meant to be a decisive Ghost King, he ends up reincarnated into a ditsy, cute and harmless hostage prince in a neighboring rival nation…

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