One day, while Shuji is shopping in Sapporo, unknown bombers attack the city in broad daylight. He and his friends run for cover, but notice a fast and small flying object shooting down the enemy bombers. Separated from his friends, Shuji wanders through the wreckage - only to stumble upon Chise; here she has metal wings and weapons - apparently grafted onto her body. She tells him she has become the ultimate weapon, without her knowledge or consent, and that she is seen by the Japan Self-Defense Forces (JSDF) as the last hope for defending Japan from imminent invasion. In the anime, it is not apparent why Chise was chosen to be the ultimate weapon or why the country is under attack. It was not until the OVA episodes were released that an explanation for Chise being chosen was offered: her body has the highest degree of compatibility with the weapon system. (In fact, later in the OVA it is mentioned that Chise had been "over-developed" and was so much of a weapon that she would kill anyone regardless of what side they were on. This fact is punctuated by Chise vaporizing the Special Forces building where she first became the ultimate weapon.)