Rise of the Devourer - Chapter 43: Mistakes

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

She, a 21st century mercenary queen, had crossed over into a tragically betrayed body of a waste. Waste? She will show them what it means to be a waste! Betrayed? With the Ancient Manual in her hands, she will astonish all the despicable men and cheap women!

Wait! Didn’t everyone say that she was an evil woman which everyone feared? Why is his Third Highness, full of mystery and charisma, so interested in her?

- Description from Novelupdates

When Ye Qing Ran wakes up, she finds that she has transmigrated into a book. She has become the vain, domineering, and evil villain who dies a tragic death.