Harmony is AmiYumi's self-proclaimed biggest fan, making her debut in Dis-Harmony. Whenever she sees them, she says "I'm your number one fan" (Number One Villager in "It's Alive"). Because she likes them too much, she appreciates anything either of them give to her. She once hypnotized herself with a lollipop she used while trying to hypnotize Ami and Yumi. She is a member of the Junior Tapeworm Scouts.
Harmony is a small girl with blonde hair in a flip curl and blue eyes. She generally wears a pink blouse, green overalls, a green bow in her hair and black shoes. Briefly in the series premiere, Harmony was seen wearing Ami's white childhood bunny pajamas. In Puffy B.C., she was seen wearing a brown-orange dress and bow. In Junior Tapeworm, she's seen wearing a green and ochre scout shirt, a dark green skirt, green socks in dark green shoes, and a pink tapeworm hat. In It's Alive, she was seen wearing a broad brim hat, a shirt, a skirt and Mary Janes.
- Due to her behaviour seen in the show, Harmony represents a stalking-type fan, a person (sometimes psychotic) which knew all of their favorite celebrities' details in every second.
- In the game, Hi Hi Puffy AmiYumi: Kaznapped for the GameBoy Advance, Harmony appears as the main antagonist and final boss of the game. After defeating her first phase, where she was disguised as Eldwin Blair, the second phase of her fight commences. The stage she's fought in is called Dis-Harmony, named for the episode in which she debuts. In this phase, she has several attacks that will make you switch between Ami and Yumi constantly. She can fire hypnotic energy pulses which can daze Ami or Yumi from her eyes, throw her lollipop at the band, teleport around the stage, rise up from the ground to taunt Yumi, summon a horde of photographers to charge at you, run around the arena, and envelop herself in one of four energy balls, all of which must be broken with Harmony hiding in the last orb. Her Hypnotic Eye attack can put you at a disadvantage if she's standing right where Tekirai is and either Ami or Yumi are trying to heal.
- She’s liked and/or hated by the HHPAY fandom, some fans find her cute or just annoying and creepy.