Masami is the spoiled-rich daughter of the owner of The Rainbow Factory. Her voice is first heard in "The Dress" when she offers to fly Gumball over a puddle. Her first major appearance was in "The Pressure," where she pretended to like Darwin to impress the other girls. She is Darwin's former love interest.
Being the daughter of the owner of the Rainbow Factory, Masami is very rich and also a bit of a snob. She has a smug sense of superiority to her fellow students, which is why she's seen pretending to like Darwin in "The Gumball's Friends VS The Penny's Friends," since having a real boyfriend was seen as impressive by the other girls who all had fake boyfriends. Masami is also arrogant, as seen by her strong dislike of Molly's Treehouse, which she thinks is really boring; that could mean that she's got fancier things at her home. She is also somewhat vain, since she hates getting her hair wet and she sees herself as being better than most of the other girls. In addition, she threatens to fire the parents of anyone who disagrees or annoys her. When she gets angry, she turns grey and zaps the person who angered her.