Knowledge from the ninja, Japan's secretive feudal spies and assassins, is the secret behind the new official ball for the upcoming World Cup, one Japanese researcher has said.
Players during the 2010 World Cup in South Africa complained that the "Jabulani" tournament ball had tendency to "knuckle" in a zigzag through the air, prompting German firm Adidas to come up with a more reliable ball for this year's tournament.
The result, known as the "Brazuca" after a slang word for native Brazilians, should fly with greater stability, said Takeshi Asai, a professor of sports science and head of the Institute of Health and Sports Science at the University of Tsukuba in Ibaraki Prefecture.