Ao no Souyoku: Phantom of Dragon

Synopsis

"Women shouldn't pilot airplanes." Ignoring this superstition, Alicia will do whatever is necessary to be able to be a pilot and protect the skies, although that means being mistaken for a man. Aaron, her brother, doesn't mind wearing woman's clothes and taking the role that was supposed to be his sister's. The wheel of fate gradually begins to move for these two twins... (Source: Japanese Publisher, translated)