A "soft reset" is like giving your electronic device a small restart. It refreshes the system without deleting any important data or settings. It can help fix minor issues or glitches that the device might be experiencing. Full definition
Back on topic though, they once read out a letter from a listener who claimed to have found a fourth playable character hidden in the game, and by doing a set list of actions and then soft resetting you could access him, and he was meant to be game director Koichi Ishii. (seikens.com)