Hundreds of years ago, the first ninja was trained. He was a true master of armed martial arts and stealth. He swore to protect his city from the shadows, eliminating all threats to the welfare of the city. But he grew old, and realized that when he died his city would be without a guardian. Thus the first ninja academy was opened. It began in a small dojo in the slums. But as the need for an army disappeared due to the acts of these shinobi, people took notice, and the sensei's school expanded. Soon it was a respected establishment and many people attended. Years passed, and the old sensei died.
The concept of the ninja was adopted by other cities. These cities became the hidden villages. Then, chakra was discovered. Chakra is the combination of physical and mental energy. It had many uses, and soon eclipsed the teachings of the old sensei. This birthed a new generation of ninjas; a generation which has forgotten what it means to be a shinobi..
These "modern shinobi" think they need flashy jutsus and honor codes. They see martial arts as a means to make an opening for them to use a "finishing ninjutsu".
Ninjutsu. A simple word. A ninja technique. But ninjutsu is a butchered word. True ninjutsu is the artful combination of armed martial arts, poison, and stealth into a style as efficient as it is deadly. But the true meaning is forgotten by academy students, genin, chûnin, jônin, and even the greatest kages. A pitiful few can even come close to calling themselves ninjas, but these few are the best of the best, all of them legends.
Momochi Zabuza. The master of silent homocide and the creator of the only modern ninjutsu I use: suiton: kirigakure no jutsu. S-rank.
Hatake Kakashi. Former Captain of the Ansatsu Senjutsu Tokushu Butai no Konohagakure. S-rank.
Densetsu no Sannin no Orochimaru. S-rank.
Uchiha Itachi. Murderer of the Uchiha clan. S-rank.
Densetsu no Sannin no Jiraiya. S-rank.
But I digress. I wish to find an apprentice worthy of my training. I will not leave this earth without a legacy, for I fear the world of shinobi will crumble without the resurgence of proper ninjutsu. And so I arrive at the gates of Konohagakure no Sato in search of a student.
I am the deadliest man alive, yet I have no bingo book entry because I have never been seen on the job. I am responsible for the mysterious deaths of 7 kages, 921 jônin, and 477 chûnin.
My name is Akatoshi Onryou, and I am the last true ninja.