Atro Spiker

Atro Spiker is an old warrior who specializes in fighting Kyouma and was the master of Adlet, who taught him to laugh at whatever is going to happen, since laughing is the best way to become strong. Atro is known for his insane, torturing lessons which led to every student, except for Adlet, running away from him. Atro taught everything he knew to Adlet in order to allow him to be the world's strongest and to also beat kyouma. Atro is also knowledgeable in science and weapon-making.

History
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.

It is mentioned that, thanks to dedicating his life to science, he manages to amass a fortune. However, after Tgurneu sent his minions to kill one by one his relatives leaving him alone, he seeded a great hatred toward the Kyouma and dedicated his life to perfect methods to exterminate them.

Despite his efforts, he became old and realized that he needed a successor, an apprentice.

Atro asked for help from the saint of words to make sure that his students harbored hatred towards the Kyouma and willingness to become heroes, and of course...they were not behind the secrets of his technology.

He trained Adlet, who could be considered his worst disciple and told him that he would be the strongest man in the world once he felt love and desire to protect something, instead of just seeking revenge.

Apparently, when only Adlet remained as his pupil, he gave him the last test that consisted of trying to kill him once a day. If Adlet not succeed at least once, he would expel him from the mountain.

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 at 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.

Training
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.

Adlet Mayer is the only known person to have completed his training, which took eight years. This included him studying almost everything known about Kyouma, weapons, and various other skills.