Sony Corp.'s new dancing, egg-shaped music player rolled into a dimly lit Tokyo hotel Monday, blinking its flaps and flashing its lights in time to each tune it played.

The $354, 11-ounce Rolly, set to go on sale in Japan Sept. 29, is small enough to fit in your palm and comes with stereo speakers, 1 gigabyte of internal flash memory and a battery good for about five hours of music.

The smooth, white Rolly also can spin in place so fast it turns into a blur, and its sensors enable a user to control volume by turning the player clockwise or counterclockwise or switch tunes by pushing or pulling the gadget.

• Click here to view a Sony ad showing the Rolly in action.

The Rolly doesn't have an American counterpart, but it will go up against Japanese robot maker ZMP Inc.'s Miuro at home. Miuro, which looks like a white ball caught inside an egg, wheels about in time to music when an iPod is locked onto it.

Sony plans to sell packages of moves and tunes online for Rolly. And users will be able to program the Bluetooth-capable product on a PC using software that analyzes music and produces choreography to match and then sends the programs to the Rolly, Sony said.

Not quite a pet, the Rolly won't take over from the Aibo robot dog, which Sony discontinued last year as part of its restructuring effort, disappointing avid owners. It can be set as an alarm clock, though.

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And Sony, which has been struggling to turn around its faltering electronics business, has been building anticipation for the device on its "countdown" Web site as a visual way to enjoy music that takes advantage of its robotics technology.

The Rolly, which plays MP3 files, Sony's own audio format called ATRAC as well as songs uploaded from CDs, can store more than 600 songs, though its capacity falls to as few as 100 when complex moves are added.

Plans for sales outside Japan are not yet set.