Kyōko Shibusawa, a magic user affiliated with the Cult of Gaia, moves with an enigmatic presence and a tendency for unexpected appearances. She harbors forbidden feelings for Kojiro Souma, defying her order's strict prohibitions against personal involvement. Her older sister Yuriko, also a Cult member, warns against this attachment, aware of Kojiro's role as Masakado's reincarnation and its inherent dangers.

She covertly assists Kojiro early on, gifting him a specially crafted Athame knife. This weapon proves instrumental in his defense against Cerberus. When Kojiro falls into Gagyson's trap and dies, Kyōko intervenes—though too late to prevent his death. Using her powers, she awakens Masakado within him, triggering his resurrection. This act of defiance leads to her expulsion from the Cult of Gaia.

Cast out, Kyōko becomes a wanderer. During the final confrontation against Ose, she intervenes once more, shielding Akito Kobayashi from an attack by a grief-stricken Yousuke Miura. Her protection enables Akito to perform the ritual resurrecting Saki Yagami, securing the conflict's resolution. Her surname Shibusawa combines the characters for "bitterness" and "swamp/marsh," while her given name Kyouko incorporates meanings of "capital city," "respectful/polite," and "child."