Harmonin emerges as the third Heartiel discovered, embodying the virtue of harmony. She first awakens inside a treasure chest within a department store, where the Pretty Cure protect her from a Zakenna attack. After recognizing Shiny Luminous as the manifestation of the Queen's life, she formally joins the other Heartiels. Visually linked to a treasure box reflecting her symbolism, Harmonin is often portrayed alongside it. Demonstrating her agency, she voluntarily chooses to enter the Queen Chairect—the special item housing the Heartiels—immediately after its reveal in the same episode. This decision follows her observation of Harmonin and another Heartiel, Pation, opting to reside within it. The Queen Chairect represents the Queen's heart and serves as the collective dwelling for the gathered Heartiels. Her core narrative function involves contributing to the Queen's restoration, as the twelve Heartiels collectively embody the Queen's will. Harmonin's entry into the Queen Chairect marks a pivotal step in this process, occurring before the eventual return of the twelfth and final Heartiel.