A Step into the Past - Volume 1 Chapter 6

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.

The formless ancient world was infested with despicable demons. They hunted and feasted on mankind, keeping the human civilization constantly in a weak and suppressed state.

During the first known year, a magical mountain descended into the world from the realm of the Gods. Carved on this enormous mountain was a message: ‘Heaven Prevails’…

After the Grand Descent, a name that was given to the descending of the mountain, the Three Great Sages made their ways to Mystic Mountain where they learned to harvest what we now call magic, establishing the Mystic Cults and eighty-one sacred shrines to help aid mankind with the cult’s mystic powers against the eternal fight to the death with demons.

- Description from Novelupdates

As the final dragon lay defeated, Aaran stared at the sky while the rest celebrated.[Awaiting the gods’ response...]He clenched his fists, his heart pounding. A shred of hope flickered in his eyes, only to be extinguished like always.[The attained outcome was deemed unsatisfactory.]Aaran had seen the message for the twentieth time. He had become the gods’ plaything in their desire to witness the “perfect ending”.He regressed once again, but this time as a toddler and charm being the only stat he had.But something was amiss. The world he remembered had changed. Powers that did not exist before had taken hold of the world.Tired of following the traditional route, Aaran chose to fight darkness with darkness… as the gods’ chosen necromancer!