Kaitou wa Koyoi mo Hanataba wo.

The ultimate partnership between a lady thief and her butler! "Lady Black" is a thief who wears all-black funeral dresses and targets only fine jewelry. Her true identity is Aria, the daughter of a jewelry dealer and a girl with a tragic past. One night, just as she was about to grab the jewel she wanted, a mysterious man gets in her way…! (Source: Ciao Comics, translated) Note: Includes four extra chapters.