Arthur Aogiri (アオギリ アルトゥール Aogiri Arutūru) also known as Seastorm Hero “ Leviathan ” (シートーム : リバイアサン Shīsutōmu Hīro: Ribaiasan) is a Pro-Hero who grew up in Hawaii and decided to come to Japan, being the place where his ancestors are coming from. Archie has received military training among the SEALs, in which he enrolled himself after getting his diploma from the military school he was studying in the past. He still serves as a soldier at the moment but was willing to help civilians when he's off-duty, he became a hero after returning to Japan a few years ago.
His Quirk Mershark (マーシャーク Māshāku) grants him skills of merpeople existing in a worldwide folklore. He was also given the abilities of sharks, that is to say that he have enhanced lung capacities, can swim fast, have enhanced physical power and inherited some predator instinct. He can choose to turn his lower parts into a shark tail when he needs to swim. He's able to manipulate water and to grew up scales thanks to his merfolk abilities. Having developped enhanced senses, Arthur is even able to communicate with underwater wildlife. With his strength he has and once propelled at high speed, Archie could easily shake a cargo ship colliding with it. He may even be able to generate tidal wave when using his capacities to its fullest. Due to his size, his mershark physiology can be compared to a Great White Shark or even the extinct Megalodon.