Duke is a red and black striped frog and Chocolat's magical familiar. As her familiar Duke is supposed to try his best to help her collect as many hearts as possible, but you mostly see him lounging around on her bed or sleeping. Instead of giving Chocolat advice, he makes discouraging comments. He finishes all of his sentences with '-kero' which is similar to 'ribbit' in English. He fights a lot with Blanca and often calls her a rat.

In the manga