Master Finn is RJ's father and bearer of the Shark Animal Spirit.
He trains Casey the ways of the shark in the form of Shark Sabers. When Casey was in trouble with Rinshis, this warrior came in to save him. He stopped the whirlpool Crustaceo was making. Casey assumed Finn was his master and introduced him to R.J. to find out he is his father. Master Finn criticizes R.J.'s housekeeping, it has been six years since they last communicated. Master Finn wanted to teach R.J. the way of his father's before him. R.J. takes it personally when Casey is eager to be Finn's pupil. Master Finn is the Pai Zhuq master of the power of the Shark. Finn's confidence and ego is shattered when Crustaceo takes over his Shark spirit zord temporarily. Finn never got over R.J. wanting to finding his own animal spirit and when he found another master, that is the straw that broke the camel's back. Dai Shi fights Master Finn and R.J. comes to his father's rescue using his Wolf animal spirit. R.J. teaches his father the way of pizza and Finn admits to the Rangers that thanks to them, he is proud of him. He's see again in Phantom and The Beasts telling RJ that the stars were in a really strange alignment yesterday while he was working on something. RJ pointed out something else that he was working on and all Master Finn could say is, "It's just in case we need a bit more light when it gets dark out." He is then captured by Phantom Beast General Whiger and taken prisoner where his spirit would be used to create the Shark Spirit Ranger. He returns later on with the other masters to test the rangers if they can earn their Order of the Claw master status. However, he fails Casey. By the end of the series, he took part in the final battle and like his fellow Masters, reached the highest level of his animal spirit in order to defeat Dai Shi's forces. He was present when Dai Shi was destroyed.