Atro Spiker is an old warrior who specializes in fighting Kyouma.
Despite being a human, he has lived for more than 700 years.
Fremy tells Adlet that Atro Spiker was one of her targets, but he was not a priority because of his age.
However, Atro Spiker was another pawn of Tgurneu in his plan to make Adlet the strongest man when he revealed him to be the seventh Brave during their encounter on the Temple of Fate. His training deemed it necessary for him to see the despair Adlet would feel being made the strongest by the Kyouma he hated.
Atro teaches his students the techniques, knowledge and skills to fight Kyouma and become a true warrior. This training method is cruel. People from various places in the continent come to him so he can teach them but it is said that, due to the difficulty, none of them were able to complete their training. Although Adlet claims his ways weren't the best, his training made him the strongest man in the world.