From ADV:

The time is the Taisho Era (1912-1926) and the incredibly powerful android, Steel Angel Kurumi, created by a brilliant scientist, was supposed to have used her super-human strength on behalf of the military. However, Kurumi cannot be activated by her makers, and lies in the machine equivalent of a coma.

Nakahito, the son of practitioners of the magical technique called "Onmyo Way," stumbles upon the inert goddess, and struck by her amazing beauty, gently kisses her perfect lips. With this kiss, the Steel Angel Kurumi comes to life, and Nakahito becomes her master. The gorgeous and voluptuous Kurumi will now do anything to protect her master.

But first, critical questions about Kurumi's origins must be answered: "Why and where was Kurumi created?" "Who created her?" Nakahito and Kurumi set out on a dangerous search to find the answers to these questions and along their journey they are forced to ask an additional question: "Who is behind the insidious activation of other Steel Angels whose only mission is to destroy the beautiful Steel Angel Kurumi?"