Steel Angel is an android who has an Angel Heart created by powerful magic. In other words Steel Angel is a creature of both science and magic. Kurumi is the 1st Steel Angel, and she is awaken when Nakahito kisses her. Nakahito is the second child of "Onmyoudou Shuke" (a house of Japanese Yin and Yang spiritual leader). She has so much affection for him that she calls him "my master".

She never follows any other orders but Nakahito's. Now, Nakahito, a boy with a gentle heart, and Kurumi, an android with an Angel Heart and invincible power, are the dynamic duo! Then the 2nd Steel Angel Saki, the 3rd Steel Angel Karinka and more characters join the story. Steel Angel Kurumi is the romantic action drama of cute girls full of laughter and heart-warming stories. The story takes place in the "Taisho Roman" period. Taisho is the Japanese historical period of about 90 years ago (similar to Sakura Taisen).