Kyoya Tachibana, a summoned otherworlder from Japan, arrived in the Central World roughly two years before the Jura Tempest Federation incidents. Initially summoned by an unspecified western nation, he later fell under the control of the Kingdom of Falmuth and the sorcerer Razen. This separated his experience from fellow summoned individuals Kirara Mizutani and Shogo Taguchi, who were directly summoned by Falmuth and had endured three years in the Central World. He appeared as a Japanese teenager with very light brown hair and dark brown eyes. Kyoya typically wore a military-style uniform but adopted civilian clothing during infiltration operations within Tempest. He often kept his eyes closed when not seriously engaged. Kyoya displayed a calm, intelligent, and aloof personality, frequently masking his intentions behind a relaxed facade. Unlike Kirara and Shogo, he harbored no resentment towards his summoning. Instead, he exhibited intense curiosity about the new world's magic and skills, viewing them as opportunities for personal empowerment. This perspective fostered pronounced arrogance and overconfidence, leading him to believe his abilities surpassed both average natives and fellow otherworlders. He cultivated a self-assured and detached attitude, showing little attachment to his original world and focusing solely on acquiring new powers. Behind a superficially friendly smile lay a rude and sadistic nature; he derived pleasure from toying with adversaries before delivering fatal blows, behavior likened to a cat playing with prey. Assigned by Falmuth alongside Kirara and Shogo to instigate conflict within the Jura Tempest Federation, Kyoya participated in covert activities designed to destabilize the nation and provide Falmuth with a pretext for invasion. During this operation, he took part in provocations that escalated tensions, culminating in an incident where Gobzo sacrificed himself to protect Shuna from Shogo. Kyoya met his end during the subsequent Tempest Holy War. He engaged in combat against Tempest warrior Hakurou and was defeated and killed in this encounter. His death, along with those of Kirara and Shogo, marked the conclusion of Falmuth's attempt to undermine Tempest using summoned otherworlders.