Beta

Beta (베타) is one of Sophia Amae's "children", and Horyang's and Cassano's "brother". He is a living ignition weapon. Before he left Horyang and Cassano, he explained that he doesn't find interest in "halfies," which can possibly mean that Beta, unlike Horyang and Cassano, who hold halves of their Demon, may be an ignition weapon that carries the powers of an entire whole Demon.

Appearance and Personality
He's a short boy and wears a blue hooded jacket. He's got bandages that cover eyes and hair. We can see underneath blue shiny veins that cover his body. He is moving around with a dropper, which gives him constant perfusion of some chemicals, we do not know as for now if those are part of the transformation process in living ignition weapon or if it provides medication for any side effects it may induce.

According to Sophia, he has a lonely and suspicious personality and has always lived in the laboratory. His statement on his  "brothers" as being "halfies" may hint that he has a complete "demon" inside of him.

Archimedes
Beta found Hatsu spying and decides to fight him, but is interrupted by Cassano and Horyang. After that is presented both as his brother, Beta underestimates them calling the "halves", then leaving them alone with Sophia.

Battle X Gamble
During the confrontation of Viole, Beta smiles at see his power. After having illegitimately entered Viole's personal room allocated to him for the tournament, he confronts Viole and claims to be the same as him; "a living weapon".

Beta