Hozuki, Kazuki, and Hazuki, three sisters descended from Galileo, have radically distinct personalities and interests; they never see eye-to-eye. The girls are attacked one day by an unknown group. The group was looking for the "Galileo Tesoro," which was supposed to have been found by Galileo Galilei. After the unexpected attack, the sisters flee on the airship they made, still clueless of what was going on. But it won't be easy for these three sisters to aid each other in a situation if they're continuously at conflict. What exactly is the Tesoro, and what is the group aiming for? What about the sisters' relationship? It's a trio of adorable females, action, and mystery!