Kyoko Shiba became Jiro Shutendo's adoptive human mother after the oni Senki presented the infant to her and her husband Ryuichiro Shiba at a temple, following Senki's victory over another oni. Senki warned he would reclaim the child in fifteen years. Despite initial hesitation, Kyoko insisted on keeping and raising the baby. They named him Jiro Shutendo, deliberately withholding their Shiba surname due to fears of attachment.

Kyoko raised Jiro protectively, aware of his demonic origins and nightmares. When violent oni-related visions plagued his teenage years, she comforted him through the episodes, even as he hallucinated her as a monstrous oni. Ryuichiro simultaneously researched demonic folklore to understand Jiro’s fate. After Senki reclaimed Jiro on his fifteenth birthday, Kyoko suffered a shattering mental collapse. Her overwhelming grief manifested as severe psychosis, leading to institutionalization. During her confinement, she obsessively painted frenzied depictions of oni across the asylum walls. Unbeknownst to her family, these paintings physically manifested a parallel dimension: Ongokukai, the demon world.

These paintings formed a devastating causal loop: Kyoko’s madness unwittingly birthed the oni race and their realm, which later orchestrated Jiro’s abduction, thereby triggering her descent into insanity. This paradox established her trapped soul as the creator deity Dai Ankoku Shiya Jarai within Ongokukai. When Jiro and allies journeyed to the demon world, they discovered Kyoko's soul imprisoned as the architect of the oni’s existence and suffering. To break the loop, Ryuichiro destroyed the asylum paintings with a sledgehammer, severing the link between her psyche and the demon dimension. This act freed her soul and dissolved Ongokukai.

Liberated, Kyoko regained her sanity and reunited with Jiro. In a reversal of their initial caution, she and Ryuichiro formally accepted him as their son, bestowing the family name Shiba.