The ninja is one of Japan's oldest and most mysterious professions. In the 15th century, young men were hired by samurai or feudal lords to spy, sabotage and kill.
But today there are only a few true modern ninja left; they are grand masters who hold the secrets of the deadly art and it can take a bit of effort to find them.
I traveled five hours by train from Tokyo to the town of Iga in Mie Prefecture. This is where some famous ninja were believed to have lived hundreds of years ago and a museum has been created chronicling their history. But very few official documents exist that mention the role of the ninja which has added to their mystery.
Their dark outfits covered everything except their eyes which meant they were virtually invisible in the shadows. They were skilled assassins, using weapons like the shuriken, or ninja star, to take out their targets.
Jinichi Kawakami is the chairman of the new ninja museum and shows me how to throw one. It's sharp and flat and the ninja's target wouldn't even have heard it until it killed them.
An authentic master of ninjutsu martial art, Kazuki Ukita poses in Ninja costume at the Ninja museum's Ninja residence in the small ancient city of Ueno. (Photo TOSHIFUMI KITAMURA/AFP/Getty Images)
Kawakami is also the 21st head of the Ban family which was one of the 53 families that formed the renowned Koka clan of ninja. His clan is one of the most famous, due in part to his predecessors' services to powerful feudal lords in the age of civil wars.
But despite having learnt all the traditional ninja skills from a young age, Kawakami trained as an engineer and worked in a company for many years. "You cannot make a living being a ninja!" says Kawakami. "From the very beginning, ninja had day jobs. There are many theories about what they were but some ninja were believed to have been farmers who waited for an order. Others were peddlers who used their day jobs to spy."
Most of the ninja's work was covert and the lack of official documentation means filmmakers, novelists and comic artists could use their wild imagination to create the ninja myth. Hollywood movies have mostly portrayed them as super human, who could run on water or disappear in the blink of an eye.
Kawakami dismisses these claims and says that "no matter how much you train, ninja are still human beings. We're taught to let people believe what they want to believe about us, so I don't want to tell ninja fans that what they think of us is wrong. But I also want them to have accurate information about our clans' heritage and that's why I teach our history at a university."
As well as espionage, assassination and sabotage, ninja were also skilled in making explosives and mixing medicines. But Kawakami admits that traditional ninja skills have little place in today's world, where guns have replaced shuriken, and spying and sabotage are best done on the Internet.
Kawakami has decided not to take on a protégé. So when he and the last few true Ninja die, the once-feared secret assassins will live on in the hourly performances on ninja tricks at the Iga museum and through the fictional characters in cartoons, movies and computer games.