Souei is a major supporting character in the anime and light novel series 'Tensei shitara Slime Datta Ken' (That Time I Got Reincarnated as a Slime). He is a loyal subordinate of Rimuru Tempest and serves as the leader of the Shadow Squad, specializing in espionage, intelligence gathering, and assassination. Calm, reserved, and highly skilled, Souei is fiercely dedicated to Rimuru, often carrying out covert missions to protect Tempest and further its interests. His ninja-like abilities and composure make him indispensable.