A high school student in Fukui was arrested Thursday on suspicion of uploading a computer program to the Internet that deactivates the expiration date in the free-trial edition of Microsoft Office 2013, police said.
The third-year student in the city allegedly made the "cracking tool" available for download via his blog in October, prompting roughly 7,000 downloads through July.
It is the first time Japanese police have arrested someone in connection with a piece of software that can deactivate Microsoft's restrictions, according to the police.
The name of the 19-year-old, who was detained on suspicion of breaking the unfair competition law, is being withheld because he is a minor.
Investigators allege that the teenager made the software tool available to raise ad revenue on his blog and that he made around ¥400,000 from the deal.