Aburidashi

From Wikipedia, the free encyclopedia

Aburidashi is a ninja technique of sending secret messages using a form of invisible ink.[1] The technique uses ink made of juice extracted from soaked and crushed soybeans.[1] The message becomes visible to the recipient by heating the paper.

References[edit]

  1. ^ a b "Japan ninja student gets top marks for writing essay in invisible ink". BBC News. 10 October 2019. Retrieved 2019-10-10.