Gulf Stream, operating under the alias Gulfstream Sasamoto, serves as an antagonist within the Big Bang Organization, a group commanded by Taiki Amanogawa (Big Bang). His initial appearance occurs in episode 1 during the semifinals of a borg battle tournament. He directly confronts the protagonist, Ryūsei Amanogawa, as his opponent in this climactic bout. This confrontation unfolds within an in medias res opening sequence, presenting the battle devoid of prior context regarding the characters or their connections. The documented sources offer no additional details concerning his background, character development, or subsequent appearances beyond this specific role.