This story tells about twins named HAYAKAWA Ukyou and NARISAWA Sakyou. Sakyou likes to wear girls clothing, while Ukyou stays with her parents and is a tomboy.
Sakyou has an allergy towards the female gender. He may either drop unconscious or explode when a female holds him. Ukyou is an exception. When Sakyou finally returns from studying abroad in the US, he is accompanied by a guy named Karl Evans, a prince of the Guten Tag kingdom who gave him (he didn't know Sakyou is a boy) an ultra-expensive and precious ring!
Sakyou convinces Ukyou to switch their identities, which ends up creating a complicated situation involving the ring, kidnapping, and monarch business. What will happen between the three?