The Great Core's Paradox - Chapter 219: Blood And Mana

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.

Yin Shen’s name is God.

He never thought that one day he would really become a god.

- Description from novelbuddy

She is intelligent, beautiful, calm, and professional. As the youngest chief forensic investigator for the past few years, her future was very bright. All of this, however, changed with a bizarre time-travel.

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