Shinobu Kai is a pilot in the Aki Team, the air division of an exploration and defensive force. He operates Rugger #2, a Mobile Strato Weapons Module that serves as the upper torso of a combined super robot. His team is one of three five-member units, alongside Sea and Land teams, which together command fifteen individual Rugger vehicles. He functions within a structured team dynamic under the leadership of Manabu Aki, carrying out missions of galactic exploration and defense against the Galveston Empire.