Japan has launched an investigation into a possible battery defect in first-generation iPod nano models following a report of one of the devices shooting out sparks while recharging. Citing an official at the trade and economy ministry, the Associated Press reports that a defect is suspected in the first-generation iPod nano, model number MA099J/A, which was sold from September 2005 to Sept. 2006. The report states that the problem surfaced in January, and Apple notified the ministry of the problem in March. No one was injured in the incident. According to an Apple spokesperson in Tokyo, it is still unclear where else besides Japan the model in question was sold. This follows a forum posting from last week, in which an iPod user claimed that his nano “blew up,” starting a small fire that set off his fire alarm. Last October, a first-gen nano user claimed his unit burst into flames while in his pocket. The ministry has instructed Apple Japan to find out the cause of what it is categorizing as a fire and report back to the government.