Teru Momijiyama, alias Shy, is a 14-year-old Japanese middle school student and her nation’s chosen superhero. Inheriting the Heart-Shift Bracelets after her sister’s death, she transforms by channeling her heart’s resolve, her civilian guise marked by short black hair, square glasses, and a school uniform. As Shy, her hair turns white, and she dons a white bodysuit with triangular collars, a visor, gas mask, and heeled boots. The bracelets amplify her powers with emotional conviction, fueling abilities like flame manipulation and wind-based techniques. Her hero journey plunged into turmoil following a roller coaster accident where she saved lives but failed to prevent critical injuries to Iko Koishikawa. Public blame and self-doubt spiraled into a depressive episode, stripping her transformation ability until witnessing a boy, Daigo, emulate her heroism during a fire. Reigniting her resolve, she reclaimed her powers to rescue a mother and child, redeeming her public image and forging a friendship with Iko, who later joined her school. Struggling with crippling shyness and anxiety, Shy battles persistent self-doubt yet perseveres with empathy and tenacity. Mentored by the Russian hero Spirit and buoyed by Iko’s friendship, she learns to merge vulnerability with courage, confronting guilt from the roller coaster incident. Her combat skills include flame attacks like "One Stroke" and "Bonfire," wind-powered whirlwinds and cloning via Utsuro Karakururi’s ring, and a temporary Scar Transformation mirroring her sister’s ferocity. After losing her bracelets post-Tokyo crises, she operated as Shadow Girl, leveraging partial transformations and borrowed powers. Pivotal clashes include facing Stigma, leader of Amarariruku, whose cursed rings exploit emotional wounds. When Stigma’s ring intensified Iko’s survivor’s guilt, driving her to near-suicide, Shy’s intervention deepened their bond and underscored her role in healing trauma. Leading missions against Amarariruku, she demonstrated tactical ingenuity, repurposing railways for evacuations during attacks. Her empathy even swayed foes like Stardust, who acknowledged her ability to connect with hearts. Rooted in her grandfather’s teachings at her sister’s funeral—that bonds and kindness define life’s purpose—Shy evolves from a hesitant novice to a steadfast leader, balancing insecurities with an unwavering drive to protect others.