An anime television series adaptation written by Reiko Yoshida and directed by Kazuo Sakai began airing on July 6, 2007.

Ten years before the story's opening, strange insect-like creatures known as "Mushi" began appearing.

At the end of episode one, protagonist Daisuke "Kakkō" Kusuriya encounters a young girl named Shiika Anmoto.

However, unbeknownst to Kakkō, Shiika is an escapee from a secret prison known as GARDEN where those possessed by the Mushi, known as the Mushitsuki, are held.

GARDEN's military force, the Special Environmental Conservation Executive Office, dispatches its finest killer to track down Shiika.