Tamaki Teijo is Haruka Hani's reserved and introverted best friend, contrasting sharply with Haruka's energetic demeanor. She has black hair cut in a chin-length bob, red eyes, and wears black-rimmed glasses. Both attend Hinomori Academy Middle School as drama club members, where Tamaki dons the standard school uniform. An orphan evacuated to Hinomori city during childhood, she resides in a temple functioning as an orphanage. There, she befriended Fusanosuke Hoegami, an Earth Wolf hostile toward the Heart Princesses. Tamaki bears a peony mark symbolizing the virtue of Tei (respect) on her lower abdomen.

Her character arc pivots when transforming into Black Princess, but during episode 6's metamorphosis, corruption twists her into a Zaiju (Beast of Sin). In this state, she assaults the other Heart Princesses, cementing her role as a primary antagonist.

A divergent iteration emerged in the 2013 pilot episode: light brown-haired and hazel-eyed, this Tamaki exhibits an outgoing personality. Surviving a plane crash, she was horrifically reconstructed into a robotic entity after being sucked into a functional plane engine, becoming the inaugural enemy faced. This version possesses white skin, light blue hair, doll-like joints, and a cannon-like structure at her head's rear.

Unconnected to the main anime continuity, this pilot variant surfaces sporadically in the core series as fleeting background Easter eggs.