Pyuan emerges as the fourth Heartiel discovered, embodying the virtue of purity reflected in her name. Her snowflake symbol visually reinforces this association. She physically manifests in episode 13 within the Garden of Rainbows (Earth), initially observed admiring the inherent purity within human hearts.

Pyuan exhibits a particular fascination with Nagisa Misumi's pure-hearted nature, frequently marveling at this quality to the point of annoying Seekun, the first Heartiel. This admiration forms her primary interaction with the main characters during her active period. Her narrative function concludes in episode 16 when she voluntarily joins the other collected Heartiels within the Queen Chairect, the artifact housing the Queen's heart. This act directly enables the restoration of the Queen's complete form.