WonderSwan is a handheld game console released in Japan by Bandai in 1999. It was developed by the late Gunpei Yokoi's company Koto and Bandai. The WonderSwan was made to compete with the Neo Geo Pocket Color and the market leader Nintendo's Game Boy Color (even though the developer for the WonderSwan, Gunpei Yokoi, developed the original Nintendo Game Boy).

The WonderSwan Color is a handheld game console designed by Bandai. It was released on December 30, 2000 in Japan, and was a moderate success.

The original WonderSwan had only a black and white screen. Although the WonderSwan Color was slightly larger and heavier (7 mm and 2 g) compared to the original WonderSwan, the color version featured 64k of RAM and a larger color LCD screen. In addition, the WonderSwan Color is compatible with the original WonderSwan library of games.

Prior to WonderSwan's release, Nintendo had virtually a monopoly in the Japanese video game handheld market. After the release of the WonderSwan Color, Bandai took approximately 8% of the market share in Japan partly due to its low price of ¥6800 Japanese yen (approximately $59 USD).

Another reason for the WonderSwan's success in Japan was the fact that Bandai managed to get a deal with Squaresoft to port over the original Famicom Final Fantasy games with improved graphics and controls. However, with the popularity of the Game Boy Advance and the reconciliation between Squaresoft and Nintendo, the WonderSwan Color and its successor, the Swan Crystal quickly lost its competitive advantage.

Before a WonderSwan can play games, the player must enter some personal information. The personal data screen can be reached by pressing the start and power buttons simultaneously. It requests a name, birthday (year, month, day), sex and bloodtype. The name will appear under the Bandai logo when the system is turned on. Option settings for default volume and contrast may also be set here.