So the genre is called “Chip Tunes” and it involves hacking something (like a Nintendo System in the case of Anamanaguchi) and composing something directly on that device. Anamanaguchi then plays live with these sound samples. You might hear about this in Scott Pilgram vs. The World which is based on this type of 8-bit sound composition. There is a game , same title, for x-box based on this video and Anamanaguchi does the sound. Check it.