Klash Ball

Makinota Show
Hold Right on the second controller, then press Reset. A simple sound test menu will appear. Press Select to choose a music or a sound effects to listen. Press Up / Down to select between music/sounds. Press A to listen.

Surprisingly, no one of the credited developers has name Makinota.

Sound Tester
Even more sound testing is possible. At the title screen, after a message "PUSH START BUTTON" appears, press Right + B on the second controller, and A + B + Down + Start on the first controller simultaneously.

For the first controller: use the D-Pad buttons to select one of the sound channel's control bits. Press A / B to toggle between bits 1/0. Press A / B at the same bit more times to increase/decrease data value, starting from the selected bit. Press Select to choose the sound channel. Press Start to send control bits to the channel and listen to the resulting sound.

For the second controller: press Up or Down or Right to view various simple endings. Press Left to view final ending and credits. Press A to exit from the Sound Tester.