Chihaya, titled "the Forgetful," served as a high courtesan in a Kyoto brothel during the turbulent Meiji Restoration. Plagued by amnesia after wielding a mystical wand to cast a luminous spell that halted the Bakumatsu wars at Edo Castle, her sacrifice erased her memories, earning her epithet and a name meaning "Destroyed Knowledge." Concealing her Elven lineage, she maintained ties to the Shield of Light—a faction resisting the Inferni’s plot to resurrect the Dark Lord—and was the younger twin of Anna, a fellow Shield member.

Within the brothel, she discovered Sonya, a captive Elf girl, and shielded her from harm. To prove her kinship, Chihaya revealed a magical hairpin that functioned as both wand and key to Hakodate, the northern Elven sanctuary. When Inferni agent Kōketsu stormed the brothel, Chihaya intervened, sacrificing herself to protect Sonya. Contact with the hairpin reignited fractured memories, allowing her to sever Kōketsu’s hand with a spell before her fatal wounding. With her last strength, she enveloped Sonya in a luminous barrier akin to her Edo Castle magic and charged the girl with delivering the hairpin to Hakodate.

Her death spurred warriors Izou and Raiden to safeguard Sonya’s journey north. Though fallen, Chihaya’s legacy endured: her twin Anna leveraged Shield of Light secrets to undermine the Inferni, while the hairpin’s power proved instrumental in Sonya’s eventual defeat of their foes, echoing Chihaya’s forgotten spellcraft.