Pupil gets top marks for invisible ink essay

[Still Waters]

A Japanese student of ninja history who handed in a blank paper was given top marks - after her professor realised the essay was written in invisible ink.

Eimi Haga followed the ninja technique of "aburidashi", spending hours soaking and crushing soybeans to make the ink.

The words appeared when her professor heated the paper over his gas stove.

"It is something I learned through a book when I was little," Ms Haga told the BBC. "I just hoped that no-one would come up with the same idea."

https://www.bbc.co.uk/news/world-asia-49996166

[Piney]

A video of Hatsumi, a former Tendai warrior monk calling it "Ninjitsu". 

Ninjas were a invention of the Kabuki Theater and there were never any Ninja families or schools. Just Shinobi operatives who worked for samurai clans. 

 

[aztek]

same thing happens when you write with milk, allegedly Lenin did that. and passed notes from prison.