Arthur Matsuda

Arthur is a being from Figurare and Nona/Prima's ditzy servant. He is also the person responsible for Masaharu's transformation into a doll in episode one. He normally spends his time in human form while serving as Nona's butler; when collecting the stardrops, he changes into his dog form, which is presumably a Doberman Pinscher. He cares deeply for Nona, and is concerned with her health when she tirelessly studies to perform powerful spells in order to compete with Sumomo. Beyond his ability to change forms when searching for stardrops, it is not shown he has any other abilities or powers.

(Source: Wikia)