The gPod hooks up to any electronic device — including MP3 players, telephones and TV sets — and provides varying degrees of vibration synchronized to the sound of a voice or musical instrument.
Retailing for about $243, the gPod comes with an external handset for easy control.
Ichiro Kameda, the device's inventor, said he designed the gPod for universal use and as a useful tool for long-distance encounters.
"One of the ideas is that you can use it here in Tokyo when your boyfriend in New York is talking to you on the phone,” Kameda said.
He declined to share where the concept came from, but did say it took him four years of brainstorming before the idea for a sound-synched vibrator came to him.
Close to 160 adult companies are participating in Japan's first-ever adult toy convention, according to Australian news site News.com.au, and products displayed over the three-day expo included sex toys, fucking machines, costumes and videos.
Two other adult companies have developed similar cellphone and MP3 player vibes, including British company Ann Summers' iGasm and the New Hampshire-based OhMiBod line.