September 1992. Tokyo was subjected to an all-out attack by an organization called Kyom. This was the beginning of what would later be named the "Tokyo Lost Life Phenomenon." ......

Midori Oribe, who worked as a nursery school teacher, was on the run with her children from the destroyed city of Tokyo. However, she lost consciousness once in the middle of it, and when she woke up, the children were gone. In order to find them, Midori climbed into the upper seat of the human machine Nanatwo that was on display at the museum, but it didn't work as she expected.

"Could it be... the lower seat...!" “Good answer."

Then Ryouhei Ogawara appeared. He got into the seat under Nanatwo and activated Nanatwo. Midori thought she could now find the children, but soon after she was attacked by Kyom's human machine, Burgoyle, and was caught up in the battle with no choice.

"If there's something you want to protect, ...... let me protect it with your power!!!!"

Bewildered by the situation she finds herself in, Midori is determined by the words of both soldiers and throws herself into the battle to reclaim the occupied Tokyo...