Arato Endou and his loyal hIE, Lacia, have reunited to demonstrate to the world that artificial intelligence, regardless of its brilliance, can be safely shut down. As they descend into the holding facility to confront Higgins, Lacia's AI creator, the duo must defend themselves against enemies from all sides. Among these foes are Snowdrop, a rogue hIE determined to devour Higgins, and Methode, an hIE seeking vengeance against Lacia. The world's super-intelligent AIs have unanimously decided to terminate Lacia, whom they consider a threat to humanity. With time running short and the odds stacked against them, will Arato and Lacia be able to truly unite in a society where humans and hIEs can coexist peacefully?