The Tokyo District Court sentenced a self-styled rightwinger to four years in prison Tuesday for attempting to extort billions of yen out of Softbank Corp.

Hiroshi Mori, 67, ordered two accomplices to hack into the Softbank BB computer system in 2003 and last January to steal the personal data of 4.7 million subscribers to the Yahoo BB Internet connection service operated by Softbank.

Earlier this year, Mori ordered another accomplice to contact Softbank and threaten to leak the client data unless they coughed up some hard cash.

Presiding Judge Kazuyuki Okuma said Mori's criminal responsibility "is very grave."

Mori ordered the accomplices to do all the work to lessen his chance of being arrested. He wielded power over the trio by telling them he was a rightwing hotshot. The accomplices were either relatives or acquaintances of Mori.

Takuya Mori, 35, and Yutaka Tomiyasu, 24, hacked into the Softbank computer system in June 2003 and again in January, stealing client data such as names and e-mail addresses.

Teruaki Yuasa, 62, then tried to extort money from Softbank directors.

During a Jan. 21 meeting with Softbank executives, Yuasa showed printouts of some of the stolen information and told the men that a group of Chinese men had presented the data to a Taiwanese credit-rating agency.

He told the executives that the release of such information would cause Softbank's credit rating to fall -- a situation that could be avoided by paying him billions of yen.