This crazy guy is the GAMEBOY MUSIC KING!! ;-).
Back when the Gameboy Camera came out in Japan he had to have one but more than the camera, the system came with a music sequencer. He went crazy with it and now he does live music performances with his Gameboy and other custom equipment.
On his site click on *sounds* and follow the links to his music. I recommend the ones at his label vs the one at MP3.com. Also if you want the full effect you need to listen on some good speakers turned up loud, not some cheap computers speakers turned down soft.