The series centers on the misadventures of 17-year-old Kana, a high school junior who spends her days hanging out with her besties, Mossan, Hijiri, and Pets. They live unremarkable lives, until the day a mecha falls out of the sky, along with a strange woman named Haruko. Her plans for Kana and her friends involve the force known as ATOMSK. Kana will have to risk everything to decide whether or not to help… like she really has a choice!