Shark King Neptune is the king of the sea and a love interest of Marina. He has his own court deep down the sea. He is also quite strong like Sharko the Shark. He has orca guards and a lobster servant. It seems that he likes tennis very much.
He also has a staff that can electrocute or paralyze people. Its pin code is 1.
He seem to love money, at one point, he used Marina's voice to earn money and while the contract is signed, she is kept in a jail-like room. It is unknown if he really loves Marina or he only loves her because she has a great voice and he got a lot of money from her.