Sealmaster

History
His exact history is unknown, but it is known that the Sealmaster was a mercenary for most of his life.

When he was hired to work at Crossroads High, he was initially offered to work along side Raiuko Kalpa as a combat instructor, but refused the position for his own reasons. Most of his work involves sealing dangerous and uncontrollable abilities, and maintaining those seals to allow students to practice their abilities at safe, controlled levels. The school also keeps him around in case they need to contract him to eliminate threats, although since they have to pay him extra for that, they reserve him for high level (S rank or higher) threats.

Abilities
The Sealmaster is capable of sealing abilities. Although he can seal even natural abilities (one of his more dangerous abilities, Sealed Breath, allows him to stop a target's ability to breath), his specialty is sealing supernatural capabilities. His high rank reflects that he can potentially seal any ability, able to seal even S rank abilities during combat without any need for a distraction. Higher rank abilities (SS or SSS rank) are theoretically sealable, but he needs a greater deal of preparation and a significant chunk of magical energy - a good portion of his energy currently goes to keeping Alice Strife sealed up, for example.

Even without his sealing abilities, his combat prowess is nearly at the peak of human potential, and he has access to various forms of sorcery, specializing in enchantments and countermagic. His body is nearly covered in enhancement and protection runes at all times, pushing him to beyond human levels as far as combat goes. However, his non-sealing sorcery is ill equipped to use during battle, and is mostly only used as a form of preparation.

He's an expert of most weapons, modern or archaic, and a master of several forms of martial arts. For most people, fighting him without magic would be suicidal, which sums up his usual tactic for fighting supernatural opponents.

His rank of SS does not reflect inhuman capabilities, but the fact that he can trump most S ranked combatants. Against ordinary humans, he would be around an equivalence of an A rank, primarily due to his ability to seal natural abilities and his preparation sorceries. He has a weakness against monsters who have superior natural abilities that are mostly unaffected by his sealing techniques - dinosaurs, dragons, and Roaras, for example.