Photo/Illutration Hiroshi Mikitani, chairman and CEO of Rakuten Inc., speaks about the company’s 5G wireless services in September 2020. (Ryo Inoue)

Police have found confidential information about 5G wireless technology services stolen from Softbank Corp. in a personal computer confiscated from rival company Rakuten Mobile Inc., according to sources.

A former Softbank employee who now works at Rakuten Mobile was apparently using the computer for work, investigative sources said on Jan. 13.

The Metropolitan Police Department on Jan. 12 arrested Kuniaki Aiba, a 45-year-old engineer living in Yokohama’s Tsurumi Ward, on suspicion of duplicating trade secrets in violation of the Unfair Competition Prevention Law.

Police suspect Aiba stole about 170 data files over about 30 occasions from late November to Dec. 31 in 2019, according to the sources. 

Aiba quit Softbank and began working at Rakuten Mobile on Jan. 1, 2020, immediately after the suspected data breach.

Police suspect that Aiba used the stolen information to his advantage to land a job at Rakuten Mobile.

Police in August searched the headquarters of Rakuten Mobile as well as Aiba’s workplace and confiscated the computer and other materials.

The secret information stolen from Softbank was stored in the confiscated computer, but the names of many files were changed, according to investigative sources.

Aiba worked at Softbank from July 2004, handling network construction and other tasks.

On Dec. 31, 2019, his last day at the telecommunication giant, Aiba allegedly used his personal computer and a special password given to him to access the company’s server from outside the firm and sent the obtained data in a file format to his email address.

The stolen data included information about 5G wireless base stations set up by Softbank.

Softbank officials have stated that Rakuten Mobile has used the stolen information for its own benefit.

But Rakuten Mobile officials have denied the allegation, saying, “We have not confirmed any instance in which we have used business information that an employee has obtained from his or her former job in our operation.”

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