Amy Haga, a first-year student in ninja history, received a final grade after delivering a blank paper to her university professor who had asked them to write a research essay.
In detail, a professor at Mei University in Japan discovered that Amy had written her entire article with the invisible secret ink, the Aporidashi technique of ninja fighters, who were famous for their secret operations.
"When the professor said he would give a high degree of creativity, I decided to make my article stand out from the rest," Haga told Japanese journalists. "I thought so much that I thought of Aporidashi."
To make sure that her teacher would not miss the secret text, Haga left a note at the end of the article asking him to "heat the paper". When the text appeared, the professor immediately gave the full mark, although he admitted that he had not read it to the end if the media wanted to take a picture.