Taishi Akejima, sometimes known as Hiroshi Akishima, is the son of Kōshirō Akejima and elder brother to Koyomi Akejima. His life was irrevocably altered by the sudden 2047 invasion of Earth by the alien force FOS, which devastated global cities and claimed his father's life during the initial attack; this loss profoundly motivates him. By 2053, he pilots robot weapons for the Planetary Defense Forces Alliance. He actively participates in the crucial "Planzet" or "Plan Z" operation, humanity's final counteroffensive against the FOS. This mission necessitates temporarily deactivating the global Diffuser defense shield to deploy a powerful weapon against the alien mothership. Prior to the operation, he urgently insists his sister Koyomi evacuate to Mars, driven by concern for her survival amidst the planetary crisis. His core objective remains direct engagement with the FOS, fueled by vengeance for his father's death. The operation demands he and his team defend their base against overwhelming alien forces for precisely 14 minutes while the weapon charges. This intense combat period forces him to confront the immediate peril facing humanity, representing Earth's last stand for survival against extinction.