OK, encontrou depois de alguma pesquisa. Chama-se "Chona, herdeira do ladrão fantasma", também conhecida como "A filha de vinte rostos".
Chizuko Mikamo is a young girl living with her aunt and uncle after her parents died. She behaves coldly toward them, despite their efforts to make her happy, because she knows that they are trying to slowly poison her so that they can take her inheritance for themselves. Because of her intelligence and knowledge gained from reading detective novels, she works to avoid eating the food her aunt prepares, but it is impossible to avoid all together and she still takes in enough to cause her to collapse. Her butler is revealed to actually be the world-famous thief Twenty Faces, who was there to steal Chizuko's rightful inheritance, a family heirloom gem known as the Anastasia Ruby. When he realizes just what Chizuko's been going through, however, he asks her if she wants to come with him and his band on their travels around the world. She agrees and Twenty Faces takes her back with him to join his gang, who affectionately shorten her name to Chiko. Two years pass and Chiko is now a strong thief, having learned the tricks of the trade from Twenty Faces and the members of his band. Now, with Twenty Faces and the rest of the band as her family, she has found a home at last.