[Blitz Lunar]

The Arcade version of Tetris Plus credits "N I S" alongside Kazuo Sawa for Sound, however neither are mentioned in any of the subsequent ports to home consoles. Only Iku Mizutani is credited for the GameBoy port, while the Playstation and Saturn ports credit him alongside Sinya Kurahasi and Hikaru Tamura, both of whom don't appear to have been involved with very much else.

My theory: N I S is an alias of Mizutani and only he was responsible for composing music, while Sawa, Kurahasi and Tamura were all sound guys. Could be wrong, but if so, I have no idea who "N I S" is or what it could stand for. All versions of the game have basically the same music.