Over the past 1,000 years in Japan, forcing monkeys to dance and perform acrobatics as if they were human has not only not been considered cruelty, it has become an art form.

The shows – usually held in the street – nearly disappeared in the 1970s as cars took over the roads and television gained popularity. Photographer Hiroshi Watanabe, 62, remembers seeing the performances, called Sarumawashi, regularly as a kid.

“For a while I thought it didn’t exist anymore,” says Watanabe, who moved to United States as an adult.

It wasn't until a few years ago that Watanabe discovered otherwise. In 2008, Watanabe and his wife traveled from their home in Los Angeles back to Japan so their son could be born there. They spent several months living in Tokyo after the birth, and Watanabe went looking for a new photo project. He’d been working on a portrait series focused on various Japanese art forms – kabuki characters, bunraku puppets – and wanted something similar. That’s when he stumbled onto the Suo Sarumawashi association.

The association had formed back in 1977 to try to keep the monkey performances alive. When Watanabe found them, they’d regained their footing and were operating two 600-seat Sarumawashi theaters and still performing around Japan.

Watanabe asked the association if he could make portraits of the monkeys and was given full access. With a simple backdrop, he shot the playful animals on film with a Hasselblad, capturing many with the odd getups and human-like expressions they use during performances.

The monkeys' trainers are not in the photos, but had to stand by during the shoots in order to get the subjects to perform. Even so, it didn't always go perfectly.

“I had to be very patient because it was like taking photos of a baby. You can’t tell them exactly what to do,” he says.

Back when Sarumawashi was more popular, Watanabe says the trainers came from the lower classes of Japanese society – a class similar to that of the Untouchables in India. Today that’s not the case, but like in the past, the trainers and monkeys still share a life-long bond. The monkeys take years to train and over that time form a strong relationship with their human companions.

“The trainers are like parents in a way,” he says.

Like the photos of cock fighting many photographers have made, Watanabe's Sarumawashi have rustled some feathers, especially here in the United States. He's heard people criticize the work because they feel the monkeys shouldn’t be held captive and forced to perform.

But back in Japan he says most people see Sarumawashi, and the photos, differently. It’s a cultural legacy that's gone on so long that it's accepted. In places like Europe, he says viewers didn’t flinch.

“The Europeans thought it was cute and funny and had a totally different attitude,” he says.

Watanabe's Suo Sarumawashiportraits will be at the Kopeikin Gallery in Los Angeles from September 7 to October 26.