Ninja were known just as much for their fast, acrobatic moves and deadly skills when fighting as they were for their espionage skills and covert operations.

As it turns out, one of those skills is great for staying cool during hot summer days!

The ninja way of staying cool

Like many parts of the world, Japan is experiencing record-breaking heat this summer. Most people are probably taking various measures to prevent heat stroke, such as carrying a portable fan and drinking water frequently.

One person who took to Twitter to post his own countermeasure was 習志野青龍窟 Narashino Seiryukutsu (@3618Tekubi), known as Japan's only legitimate professional ninja, a 4th dan Nindo (忍道) master and In'nin Hyojoshu Council Member (陰忍評定衆) of the Japan Ninja Council (日本忍者協議会).

Here is what Narashino did:

Reproduced with permission from 習志野青龍窟 Narashino Seiryukutsu (@3618Tekubi)

Here is the technique known as 水遁 suiton.

Hiding beneath the surface of the water thanks to weights placed on his abdomen and using a pipe to breathe, he looks just like the way ninjas are often portrayed in Japanese media and pop culture and what many Japanese people imagine when they think of ninjas.

According to Mr. Narashino, this is not the real suiton technique as described in authentic ninjutsu books, but only an approximation.

The stylish way of cooling off "ninja style" elicited many comments online, such as, "It sure looks cool, but the difficulty level is too high!" and "the image is so surreal that it blew me away!"

In case you're thinking of imitating him, please be warned. Narashino says this is a technique that can only be done by professional ninjas who have gone through rigorous training, so it is dangerous for you to try it otherwise.

By - grape Japan editorial staff.