A sergeant within the paramilitary counter-terrorist force, Mithril, he serves as a member of the SRT (Special Response Team) of the Western Pacific Battle Group "Tuatha de Danaan" and is assigned to the assault submarine of the same name. He has been assigned to spend a year living a normal life, which he has never known since he's been in combat zones since his early childhood. Despite his brash nature and lack of social skills, Sousuke is a kind and caring individual who wants to excel in all endeavors and protects those he deems as allies.