This subspecies of Metal King is said to hold within its large body a huge collection of information on the element of thunder. They heavily dislike being in crowded places as they are quite fearful. It is said that when they gather with others from the metal record species they always speak ill of humans, saying things like "Those scary Summoners want to kidnap us all." However, they are also easily fooled and are quick to let their guard down when given a compliment.
Thunder King is best used as an ingredient for fusion, providing a base of 11,012 XP. When fused with Thunder element units, it grants 16,518 XP, not including Great Success (x1.5) or Super Success (x2). The Thunder King only sells for 2,500 Zel.