A Japanese student got top marks for an essay was written in invisible ink.

Bizarre on Female First

Bizarre on Female First

Eima Haga - first year student at Mie University in Tsu, Mie, Japan - had to write about the Ninja Museum of Igaryu for a ninja history class, with the promise of high marks for creativity.

According to the BBC, the 19-year-old woman decided to use the ninja technique of ''aburidashi'' by soaking and crushing soybeans to make the ink.

The words written using this can then be read when the paper is heated over a stop.

Haga said: ''It's just something I learned through a book when I was little.''