Setsuna Higashi emerged from the dimension Labyrinth as lieutenant Eas, serving ruler Moebius with cold, calculating loyalty. Her silver hair and red eyes complemented a black-and-crimson combat suit adorned with metallic accents. Infiltrating Earth under the alias "Setsuna Higashi," she concealed her identity with dark purple hair and civilian attire. She manipulated Momozono Love, accepting a clover necklace as false friendship while persistently attempting to steal Love’s transformation device. Moebius empowered her with Nakisakebe cards, though their thorny vines inflicted agonizing pain during battles against Pretty Cure. During a decisive clash with Cure Peach, Eas sacrificed her life energy to activate a devastating weapon, resulting in her physical death. Resurrected by the fairy Akarun, she gained the ability to transform into Cure Passion. This rebirth triggered profound guilt over her past actions and initial resistance to joining Pretty Cure, overcome only through Love’s unwavering encouragement. Without a home in Labyrinth, Setsuna was adopted into the Momozono family, becoming Love’s sister. Adjusting to Earth presented hurdles: Setsuna grappled with social customs, displaying naivety in daily interactions. Lingering trauma manifested as self-doubt and nightmares, epitomized by a Nakewameke monster mimicking her Eas persona—defeated alongside her new allies. Supported by teammates Inori Yamabuki and Miki Aono, she joined their dance group "Clover," enrolled in Love’s school, and excelled academically and athletically. Her personality softened into kindness and patience, yet retained core determination and strategic intellect. As Cure Passion, she transforms declaring "Change, Pretty Cure! Beat Up!," gaining long pink hair and a red-and-black layered dress with a black hip ribbon, crowned by a heart-accented tiara. Her Passion Harp unleashes attacks like "Happiness Hurricane" and "Lucky Clover Grand Finale." Advanced forms include Cure Angel Passion with angelic wings and elongated hair, and Rainbow Cure Passion with golden wings. Her Linkrun device rests distinctively on her right hip. Her relationships trace a redemption arc: she forged a sisterly bond with Love, aided Miki in conquering fears, and reconciled with former Labyrinth lieutenants Westar and Soular post-Moebius’s defeat. Despite opposing Moebius, she addressed him as "Moebius-sama," appealing to his residual humanity. After the conflict, she returned to Labyrinth with Westar and Soular to rebuild its society. In *Precure All Stars New Stage: Mirai no Tomodachi*, Setsuna participates in the collective Pretty Cure mission to locate scattered fragments of the antagonist Fusion in Yokohama.