Short answers, pulled from the story.
The WonderSwan is a handheld game console released in Japan by Bandai on the 4th of March 1999. It was developed in collaboration with Gunpei Yokoi's engineering firm, Koto Laboratory. The system was sold only in Japan and was discontinued in 2003.
Gunpei Yokoi was the Nintendo engineer who created the Game Boy. After leaving Nintendo in 1996 following the failure of the Virtual Boy, he founded Koto Laboratory and was recruited by Bandai to design the WonderSwan. Yokoi died in a car accident in 1997 before the console launched, making the WonderSwan the final hardware project he worked on.
All WonderSwan models combined sold an estimated 3.5 million units. Of those, 1.55 million were the original WonderSwan and at least 1.1 million were the WonderSwan Color. The line captured up to 8% of the Japanese handheld market at its peak.
Squaresoft contributed remakes of Final Fantasy, Final Fantasy II, and Final Fantasy IV. Namco, Capcom, Banpresto, and Taito also developed titles, with Taito porting Space Invaders and Densha de Go!. Bandai published exclusive Digimon and Gundam franchise titles, and a puzzle game named Gunpey was released in honor of Gunpei Yokoi.
Bandai signed an agreement with Mattel in 2000 to bring the WonderSwan to North America but ultimately decided against a Western release. The exact reason was never officially stated. The crowded North American handheld video game market has been suggested as a contributing factor.
The original WonderSwan used a monochrome FSTN display with a 40-hour battery life from a single AA battery. The WonderSwan Color, released on the 9th of December in Japan, added a passive matrix color screen displaying up to 241 colors, with a battery life of roughly 20 hours. The SwanCrystal, released on the 12th of July 2002, replaced the FSTN panel with a TFT LCD screen that reduced motion blur, though battery life dropped further to approximately 15 hours.