Aku is a Japanese demon, god of darkness and fire and the eleventh recruited member of the Hall of Injustice. He's from Ancient Asia but he lives in a far-away unknown environment with no trees or grass but stone floors. There're mountains with hellish-like environments inside, which is where he lives. Plus, he's the archnemesis of Shin and Ashi. He's over 20 million years old, 8 feet and 11 inches tall or various and weighs 435 or various pounds. He has a black body, a green face, a white pig-like nose with red inside, long arms and fingers and a red beard which extended from the bottom of his chin. He has six horns, four long and two short that extended from his head, and his eyebrows were made of red, flickering flames. His teeth and lips are outlined with red. His eyes are large and circular with white sclera and tiny black pupils.He has the same voice of the same name from Samurai Jack. He's very slow-talking, dramatic, loud, silly, murderous, black-hearted, and ruthless. He is known as the Black God Master of Fire and Darkness as he owns an army of demons. The males are wrapped in red or gray cloth with green eyes and geared with black dao swords. The females have black petite bodies with pupiless white eyes, four long horns and geared with black jian swords. He also owns beetle-like robots called Beetle Drones, which have black metallic bodies, thin arms, scythe-like hands, and red eyes with diamond backgrounds. He possesses superhuman strength, durability, stamina, speed, agility, endurance, reflexes, senses, and longevity, flaming breath, heat and foresight (the black beams from his eyes are outlined with red as his foresight show red beams of light to reveal invisibility), indestructibility, immortality, umbrakinesis, pyrokinesis, telekinesis, shape-shifting, elasticity, size manipulation (up to 26 feet), ultrasonic screams (white rings of energy), telepathy, teleportation, regeneration, necromancy, space-survivability. He's mastered in hand-to-hand combat and martial arts. He and Hydra make close friends as he is one of three most powerful members of the Hall of Injustice, along with Scarlet and Hydra.