Naive, innocent, and energetic. She is very expressive and honest with her emotions, cheering with her whole body when happy, but often showing a childlike side by bursting into tears when she fears being left out or gets scolded. She doesn't seem to know much general knowledge, perhaps because she doesn't go to school. She absolutely loves sweet snacks like gelatin and sugar. She shatters easily if she falls from a height or hits a hard object. She is close with Book, Bubble, Match, and Pencil.

Self-centered and highly competitive, she is the leader of the group consisting of Ruby, Bubble, and Match. She often tries to control the group or ignores others' efforts. While she is close with Ruby and Bubble, she is extremely close with Match.

She shows a two-faced nature, being kind to those she likes while thoroughly excluding and ignoring others. She is especially close to Pencil, calling her by the nickname "Pence-Pence," and she hates it when others use that name. She has a bit of a selfish streak. She dyes her hair often. She is reasonably close with Ruby and reconciled with Bubble after a fight.

Since she is a bubble, she pops even if poked slightly. She is very kind-hearted and used to be indecisive, though she has become more assertive over time. Her friends sometimes perceive her as a dummy who can't even count to three. She has a good relationship with Ruby; her relationship with Pencil has soured compared to before, and she is back on good terms with Match after their fight.