Tokyo in the near future.
People avoid disasters and epidemics and live in the sky.
NOUNAI Senri joined the large pharmaceutical company RUOWA in order to cure the incurable disease of his older sister Mari, but he was involved in a side effect incident involving the company's RUOWA Metal drug, which turns muscles into metal, and he left the company.
Six months after he quits, the giant company RUOWA crashes into the Shitamachi district where he lives.