I would probably wait a while for the dust to settle, and then go about making subtle changes so that it's still the same game, but it doesn't appear to be Prism to Nintendo, and then just silently release it.
@Xdqwerty, Osu! Tatakae! Ouendan! is the Japanese version of the game, different settings/characters/songs but otherwise identical mechanics. I played that before I knew about Elite Beat Agents lol. Both fantastic games https://en.wikipedia.org/wiki/Osu!_Tatakae!_Ouendan