Every student's dream is surely to hand in a blank paper and get top marks.
That's exactly what happened to Eimi Haga, a 19-year-old Japanese student of ninja history, achieved. But all is not as it seems...
The essay was in fact written in invisible ink, making the writing appear only when the paper is heated.
In order to create the ink, Haga told the BBC that she did the following:
1. Soaked soya beans overnight
2. Crush them up and squeeze out any moisture in a cloth 3. Mix the soya bean extract with water and get the consistency "just right" (what "just right" actually means remains a mystery)
4. Use a fine brush to write essay on washi, a type of very thin Japanese paper
The technique is known as aburidashi, and the professor said he had never encountered an essay using it before, even though he has had students think more creatively about their assignments, handing in papers written in code.
Haga got full marks for the project, even though the content of the essay was admittedly more style than substance.
Worth a try, especially if you're a ninja student.