Japan has an annual Ninja Festa (Kids welcome!)

Iga-Ueno City's Ninja Festival celebrates Japan's famed warriors and its place in their history.

Few iconic figures are more closely identified with Japan than the ninja; a combination of elite warrior and intelligence agent whose basic mission continues in various forms to this day. "The art of Invisibility" is waiting for you to enjoy too!

For those living in the Kansai area, or willing to make the journey from Tokyo, the city of Iga Ueno, home to the Iga ninja tradition, holds a month long ninja festival each year. This year’s event runs from April 2nd-until May 5th.

Ueno City is accessible from Nagoya, on the JR Kansai line. For the festival there is a free ‘ninja train’ that runs to town from the main station.

Ueno City is accessible from Nagoya, on the JR Kansai line. For the festival there is a free ‘ninja train’ that runs to town from the main station.
During that time, Ueno Park (not to be confused with the one in Tokyo*) turns into a ninja playground. *Note Tokyo's Ueno Park also has a related Ninja Celebration

There is live action theater, games of skill; visitors can try their hand at throwing stars, or bow and arrow and a hunt for prizes which involves coded messages in various places throughout the park. This particular game would be for those who can read Japanese, but there are lots of other activities.

Many city residents including the Mayor dress in colorful ninja costumes, and there are parades along the main street. There are also stalls along the street with local and international treats. Rice crackers shaped like throwing stars is a local specialty and there’s even ninja herbal tea (!) said to ward off hunger and fatigue while waiting for the moment to strike.

Adjacent to the park is the Ninja Museum, where one can see real antique weapons and uniforms. There are also chances to try things like eavesdropping tubes (placed against a wall to hear conversations).

Also fun is a reproduction of a ninja house, with trap doors and secret compartments. The more able-bodied will have an easier time getting around, since spaces are narrow and stairs are steep.

This years (2016) Flyer, in Japanese:
http://www.iga.ne.jp/~ninjafesta/pdf/ninjafesta_flyer.pdf)

The city also has a picturesque castle, reconstructed from the original.

If time allows, it is possible to visit Koga as well-home of the other major ninja clan and just over the border in neighboring Shiga prefecture.

For those whose interest in the arts tends more toward the literary type, or with interest in both, Iga-Ueno is also the birthplace of haiku master Basho Matsuo, one of Japan’s greatest poets. The Basho memorial museum is close to Ueno castle, and about 1 km away is Basho’s birth home, which is open to visitors.

This event is unique, exciting and educational and well worth investing a weekend, especially if it can include a Friday or Monday.

More details in Japanese only at their website:
http://www.iga.ne.jp/~ninjafesta/

And they have a Facebook page too also in Japanese but with lots of great pictures for you to get an idea of what it would be like for the kids... and yourself!
https://www.facebook.com/ninjafesta