There's Something Wrong With These Demonic Women! - Chapter 216: Call Me Shuang’er

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.

Good news: I have transmigrated to Teyvat and become the Heavenly Principle.Bad news: The world of Teyvat doesn’t have much time left.Good news: I have a system that allows me to devour two-dimensional worlds.Noah looked at the countless familiar worlds, tears of sorrow streaming down his face, and announced on the spot:“I will not only be the Heavenly Principle of Teyvat but also the Heavenly Principle of countless worlds.”“So, my rules are the laws.”From then on, one Heavenly Principle and a group of fierce Gods embraced trembling worlds one after another.After devouring the world of Demon Slayer, Teyvat’s lifespan increased by 5,000 years.After devouring the world of Akame ga Kill!, Teyvat’s barriers were strengthened by 100 times.After devouring the world of Inuyasha, Teyvat forms the cycle of reincarnation.…

Childhood sweethearts.
The most popular person in school is my childhood sweetheart.

- Description from Novelupdates

After dying, Chen Heng finds that he has transmigrated to an alternate reality: everything is the same, except the world is now a Wuxia world heavily influenced by martial arts! Not only this, he discovers that he has a Fantasy Simulator, from which he obtains rewards that make him incredibly powerful in his new reality as well. Martial arts, immortal cultivation, and overpowered abilities–all of this begins from a single simulation!