After Transmigrating into a Cannon Fodder Character in the 1980s, I Trash Them All - Chapter 24

A young man finally managed to become an immortal, a powerful cultivator able to lord over millions of souls. He took advantage of his tremendous luck and fortune to become the youngest immortal in history. He now wants to create his own sect and enjoy life, one filled with female disciples!

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.

Luis, a poor 17-year-old boy, tries his luck at becoming an Awakener to change his fate. However, his dreams are shattered when he fails to awaken a Special Spirit and is instead saddled with a 5 million dollar debt by their planet's colonizers, the Flying Star Empire.His life seemed doomed—until a mysterious system suddenly appeared in his head: The Monster Transformation System. It gave him the power to transform into any monster or animal he had ever seen.From a cat to an eagle, even a horse, Luis begins to understand that his power may not come from Spirit... but from the ability to become any monster.

He lived from BC to the Middle Ages, from the Renaissance to the Industrial Revolution, and from Cyberpunk to the Interstellar Age. He has been a king and a prophet, a knight and a nobleman, a versatile artist, a genius inventor…
This is a four-thousand-year human epic——
“To us four thousand years from now:
“Is the world at peace? Is famine extinct? Can people touch the stars? How long is the human lifespan? How far is the boundary of the earth? Human…do you remember us?”
——Excavated from Earth Age Tenth Century BC, Solomon Prayer Book.

- Description from novelbuddy