Heehee. Oddly enough, I think the first boss is the most challenging because of Ryu's limited moves when you fight him and he is less pattern based than the other bosses. Your best bet is to continuously roll/dodge his attacks. Never throw shuriken at him and strike him every once in a while. He will usually block your attack, but at times he will go into a weapon lock with you. In that case, mash the attack button and you will usually win, then he will be open to attack. Attack him some and then roll away and dodge. Repeat.