The Japanese city of Iga is suffering from a ninja shortage.

The city, which is about 280 miles from Tokyo in central Japan, claims to be the birthplace of the ninja.

The mayor is hoping to bolster tourism by drawing on the city's ninja heritage.

There's just one problem: There aren't enough ninjas.

You may have heard about Japan's demographic crisis, but the country is facing another, lesser-known crisis as well.

Japan does not have enough ninjas.

In an episode of NPR's "Planet Money" podcast, Sally Herships visited Iga, a small city in central Japan that claims to be the birthplace of the ninja.

Each year the city of about 100,000 swells by about 30,000 as tourists come to experience the annual ninja festival.

Iga, however, is suffering from depopulation. "It's facing a shortage of those two key things you need to keep an economy humming: stuff to sell and people to buy the stuff," Herships' cohost Stacey Vanek Smith says.

Iga is also losing young people who don't want to live in the rural countryside. To revive the local economy, the mayor of Iga, Sakae Okamoto, is promoting the city's ninja heritage with the aim of drawing more tourists.

Women dressed as ninjas throwing "shuriken" during a ninja festival in Iga. REUTERS / Kim Kyung-Hoon

"Right now in Iga, we are working very hard to promote ninja tourism and get the most economic outcome," Okamoto told Herships. "For example, we hold this ninja festival between late April to around the beginning of May. During this period visitors and also local people come here. Everybody will be dressed like a ninja and walks around and enjoys themselves — but recently I feel that it's not enough."

Japan is experiencing a major tourist boom — the United Nations World Tourism Organization estimates that almost 29 million tourists visited Japan in 2017. That's an increase of almost 20% from the year before.

While some cities are benefitting economically from the influx of tourists, rural ones like Iga are apparently being left out.

With the hope of encouraging tourists to stay longer than a day in Iga, Okamoto is relocating city hall and building a second ninja museum in its place. While the budget is not disclosed, Okamoto has received funding from the central government from the public — "Japan's government is funding ninjas," Herships says.

The project faces some hurdles, though. Iga needs to attract labor forces to work and live in the rural city as the ninja tourism scheme is extended.

Atsushi Kobayashi a staff member of Bujinkan Training Hall watches foreign tourists train during a class which allows tourists the opportunity to experience life as a Ninja in Tokyo, Japan, Wednesday, Feb. 20, 2008. Foreign visitors have always flocked to old tourist spots in Japan like Kyoto, the Sapporo Snow Festival, hot-springs baths and Mount Fuji. These days, they're also checking out new offbeat ways to experience Japan like ninja classes, geek gadget stores and "manga" animation museums. AP Photo / Junji Kurokawa

This means not just builders and planners but also ninjas themselves. "There's a ninja shortage," Herships says, "or — to be accurate — a ninja-performer shortage."

This issue is especially difficult given Japan's extremely low unemployment rate, which is just 2.5%.

It is therefore hard to find workers in Japan, let alone highly specialized ninja performers.

"Ninja is not an inheritable class. Without severe training, nobody could become a ninja. That's why they have silently disappeared in history," Sugako Nakagawa, the curator of the local ninja museum, told Reuters in 2008.

"But this job does have a lot to offer," Herships says. "First of all, the pay is quite competitive. Today, ninjas can earn anything from $23,000 to about $85,000 — which is a really solid salary, and in fact, a lot more than real ninjas used to earn in medieval Japan."

Herships quotes the International Ninja Research Center, which states that in Iga, the typical ninja earned an inflation-adjusted $8,000 to $17,000 a year.

Okamoto faces an uphill battle, though. The Mie Prefecture, where Iga is located, as a whole attracted just 43 new young residents last year; Iga alone lost 1,000 residents.