There is a hidden spirit in the game named Shaco. Once you beat the boss, turn the game back on and go to where you first met Amidamaru. Shaco will send Rio, Trey and Len to different places (Lounge Lizard Lanes, Sunshine Building, and Mata Cemetery, respectively). Go fight and beat your friends, then go back to Shaco. You will have to fight him twice, and he is a dark spirit. Hope this helps all.