From Horobi no Michi:
Clockworkers- mechanical men, created during the war as a weapon to kill as many as possible. That war may be long over, but rogue Clockworkers are still roaming about, spreading fear and death wherever they go.
Machina's a member of the CWA, an organization dedicated to the destruction of these rogue robots.
Along with Deus, her Clockworker partner, she travels the country in pursuit of these dangerous robots...