IGA (Reuters) - In a faded black-and-white photo, an old man clasps his hands, making a peculiar sign with his entwined fingers while the handle of a long sword peeks out from behind his back.
"My grandfather never lay down to sleep, he always slept sitting in a chair as if he was on the lookout. He was also good at hypnotism," recalls 55-year-old Motoharu Murai, who says he the grandson of the ninja fighter pictured in the photo.
Some ninja experts doubt Murai's assertion because the silent assassins usually operated in secrecy and never revealed their true identity, even to their families. But Murai sees his grandfather's sneaky and effective weapons and matchlock muskets as solid proof that he was indeed a ninja fighter.
Murai lives in Iga, a city 450 kilometres (280 miles) from Tokyo and known to many Japanese as one of the traditional home towns of the ninja, the mysterious spies that slid through the streets of ancient Japan.
The quiet city of 100,000 attracts almost 30,000 visitors for its annual ninja festival, which runs from April 1 to May 6 and features ninja-inspired dance performances, competitions, and opportunities to practice ninja skills.
Real ninjas no longer exist, according to Sugako Nakagawa, curator of the local Ninja museum.
She said ninja fighters thrived during the 15th-17th century, serving different masters in Japan's warring states. But the peaceful Edo era that followed reduced demand for spies, and ninjas turned to mainstream jobs such as farming and trade.
"Ninja is not an inheritable class. Without severe training, nobody could become a ninja. That's why they have silently disappeared in history," she said.
But in Iga, ninjas are everywhere: in souvenir shops, on restaurant menus, on the signboards of shops. They are painted on walls in public bathrooms and shaped into cookies and dolls. They rake in 290 million yen (1.4 million pounds) from ninja lovers during the five-week long festival.
For tens of thousands of enthusiasts from Japan and abroad, the search for a ninja continues. As a warm-up during the festival, they dress up as ninjas and scour the streets to find hidden life-sized ninja mannequins.
Ninja-lovers try their hand at throwing "shuriken", palm-sized, star-shaped spiked metal weapons that feature in every ninja movie, and they visit a house equipped with false walls and secret escape passages where real ninja once lived.
"We don't know entirely what the life of a ninja was truly like. But the mystery stimulates people's imagination and that's the attraction of a ninja," museum curator Nakagawa adds.
(Editing by Sophie Hardach)