Tanaka's Panasonic Wild Knights club said on Saturday that the 27-year-old scrumhalf would be joining the New Zealand team in 2013.
"I feel so honoured to be becoming Japan's first Super Rugby player," said Takana. "I hope to improve at the higher levels of rugby and bring those skills back to Panasonic.
"I want to play as many games as possible and show the world what Japanese rugby players are capable of. I want to believe there's nothing I can't accomplish."