PlayStation Vita has been catching fire, but not in the way that Sony would have liked.

An official investigation is underway in Japan concerning a series of incidents in which a PlayStation Vita became dangerously hot while recharging, the Yomiuri Shimbun reported on Wednesday.

"We believe the cause [of the burnouts] is that the cable got wet or had something stuck to it," Sony said in a statement. "There is no defect."

Sony said that it is aware of 31 overheating cases in the Vita's first six months on the market. 23 of those cases took place in Japan, and eight in the United States, Europe and Australia. Sony said it does not plan to recall any PlayStation Vita hardware.

The investigation into the Vita overheating incidents is being conducted by the National Institute of Technology and Evaluation, an independent agency working on behalf of Japan's Ministry of Economy, Trade and Industry.

A list of overheating cases submitted to NITE has been circulating on Japanese message boards. All of the cases, which occurred in different regions of Japan at different times, have the same description: "The portable game machine was recharging. The cable burned out and changed colors. The cause is under investigation."

Sony posted a press release on its Japanese PlayStation website reminding consumers to "avoid exposing the Vita's multi-use cable to liquids or foreign substances."