In 2031, the world changed drastically due to a runaway accident of the "Quantum Reactor" developed as a next-generation energy device. A flash of light suddenly spread from underground, engulfing urban buildings and covering the earth. Eventually, an unknown special evolved creature "BRAI" that surpassed and integrated biology, machinery, and plants appeared. Seven years later, Xianglong was reborn as the absolute defense city "Neo Xianglong". It evolved at an astonishing speed and became the last fortress of hope for mankind to fight against BRAI, which has put humanity in danger of extinction. Leon, Keyi, Kunling, and Doug, who were guided by fate and gathered in Neo Xianglong. Cecil, Kane, Jay, and Glenn welcomed them into the defense force. Thus, the special force "Pandora" was born to fight for the survival of mankind. At the time of the contract, hope was entrusted to them-