MTL - Overlord in Cultivation - Chapter 2173 Horror world!

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.

In this world, some say, the truth and the legends are the same. One such legend belonged to the protagonist, Valerian.

Valerian was an orphan, a boy blessed with a beautiful face, and everyone around him, could not help but want to play with him, till one day a prophet passing through their town pronounced him to be cursed.

Since that day, the destiny of the boy seemed to have changed completely, he was shunned by everyone around him, and the gazes that were earlier filled with love and affection, now brimmed with disgust and hatred.

The constant shunning and humiliation made the cheerful child grow up to be bitter and inexpectant. On his seventh birthday, things changed once again.

This time, it was not the people around him who went through a change, but himself. As he grew up, Valerian became a legend in his own sense.

The people sang of a boy, who could not speak, they shed tears for a boy, who could not grieve. He came from nowhere yet he was known everywhere.

Would you like to know this legend? A story where a curse can become a blessing? A story of sacrifice, betrayal, determination, and secrets.

Let’s fight! Go! Who am I afraid of with a chip that turns into a brain cell? ! Get promoted and get rich! The nest treasures are all mine!

- Description from novelbuddy

500 years ago, Chen Xi was devoured by a crack in the void and was transported into a cultivation world.

500 years later, he returned back to Earth after enduring through several hardships and discovered that only 5 years had gone by.

…

In the courtyard, beauty at the side, a candle flame wavering.

A gush of clear wind, half a full moon, the peach tree remains unchanging.

…

Wait, whose kid is this?! Why is she calling me papa? Gazing at the little girl in front of him with skin as pale as jade, Chen Xi froze.

…

　
Returning home from cultivation, starting as a stay-at-home dad.

In this life, not fighting to be a king nor claiming to be a tyrant, only praying to peacefully be a wife-pampering mad devil and a child-protecting daddy!

- Description from Novelupdates