Yumiko Shirasagi originates as a central character from Aya Nishitani's *Digital Devil Story* novels. Following her father's job relocation, she transfers to Jusho High School in Tokyo. At school, she observes unusual behavior in classmate Akemi Nakajima and overhears a conversation between him and their teacher, Ohara. Ignoring warnings, she follows them to the Computer Aided Instruction room. There, she witnesses the demon Loki raping and impregnating Ohara. This horrific event leaves Yumiko traumatized, though she initially dismisses it as a magic trick. Loki then targets her as his next sacrifice. One month later, Nakajima warns Yumiko to avoid school, but she disregards the advice and is captured by Loki. He manifests physically, molests her with tentacles, and attacks other students. Ohara, under Loki's influence, nearly kills Yumiko by twisting her neck. Nakajima intervenes by summoning Cerberus, but Loki overpowers them. During the struggle, the goddess Izanami channels her power through Yumiko, severely burning Loki. Yumiko and Nakajima escape through a dimensional warp, though Loki fatally wounds Yumiko during their flight to Asuka. Yumiko succumbs to her injuries and the strain of Izanami's power. Before dying, she reveals her body can be revived if taken to Izanami's tomb. Nakajima fulfills this request, encountering the guardian Yomotsu-Shikome, who provides mystical spheres. Loki pursues them, captures Izanami, and uses Yumiko's corpse as leverage. Nakajima summons the fire god Hi-no-Kagutsuchi, defeating Loki. Izanami revives Yumiko but keeps her in Yomi (the underworld) to train her in using dormant powers. In *Digital Devil Story 2: Warrior of the Demon City*, Yumiko remains in Yomi for training. Distracted by her mother's voice during one session, she fails a task. Izanami permits her return to the human world. There, she discovers Ohara—empowered by carrying Loki's child—has killed Yumiko's family as revenge. Yumiko finds Nakajima battling Ohara and his demon-controlled mother. Forced to kill Nakajima's mother to save him, she flees after seeing his reaction. She pursues Ohara into Soga Forest and defeats her. The demon Seth possesses Ohara's unborn child and attaches to Yumiko, using her magnetite to merge worlds and summon demons. A week later, Seth forms a tower of flesh with Yumiko crucified at its core. Nakajima attempts to free her, but Seth's minions threaten her life, revealing her crushed eyes. Yumiko telepathically urges Nakajima to keep her alive. Seth brainwashes civilians for sacrifices, though Nakajima and Charles Feed plan to trap Seth in satellite orbit. Nakajima fails to free Yumiko during the attempt, and she is pulled into space with Seth. Seth fully manifests using Yumiko's magnetite, but Nakajima and Yumiko coordinate an attack that destroys Seth. Demons cling to Yumiko during the collapse, and she pleads with Nakajima to let her fall into the Atziluth realm to prevent further invasions. Nakajima rescues her, leaving the interdimensional door open. In *Digital Devil Story 3: Demise of the Reincarnation*, Yumiko is blind and scarred from the battle. Nakajima nurses her while both suffer nightly demonic nightmares. Yumiko receives a message, seemingly from Izanami, urging her to go to Asuka. Nakajima agrees despite dangers. In Asuka, Siren's devotees surround them, insult Yumiko's scars, and provoke Nakajima into a rage. He kills a human insurgent, leading to his arrest and death sentence. During Nakajima's execution, chaos erupts. Izanami contacts Yumiko, revealing Lucifer had sealed her power. Restored and healed, Yumiko approaches Nakajima, but he—lost in madness—attacks her. Izanami possesses Yumiko, killing Nakajima. He dies in her arms, and Yumiko, despairing, stabs herself with Nakajima's sword. Izanami, now inhabiting Yumiko's body, buries Nakajima in Asuka. In the OVA adaptation, Yumiko is crystallized by Loki and taken to Makai, diverging from the novels. In video games like *Digital Devil Story: Megami Tensei* and *Kyūyaku Megami Tensei*, she is a playable character alongside Nakajima. She begins with balanced stats and learns skills based on party level and combined intelligence with Nakajima. Her abilities include healing (Medi, Patch), support (Mapper, Etna), and offensive magic (Bottorra). She is integral to gameplay; if both protagonists die, it results in a game over. Physically, Yumiko has long black hair and black eyes. Her attire includes a Jusho High School uniform: a white shirt with a string tie, dark blazer, long skirt, and white socks. Alternate designs feature a sailor-style uniform or a red ribbon in the anime. After her injuries, she bears facial scars and blindness. Analyses attribute to her personality traits consistent with ISFJ (Introverted, Sensing, Feeling, Judging) and Enneagram Type 6 (Loyalist). She is observant, empathetic, and values-driven, often prioritizing others' safety. Her loyalty manifests in protecting Nakajima and confronting threats despite personal risk. Anxiety and fear drive her cautious decisions, though she demonstrates resilience in crises.