Ryūji Morisaki worked as a substitute elementary school teacher, filling in during a regular teacher's maternity leave. His past included military service in European theatres during World War II. He married Lisa, who died roughly ten years before the story's main events, on May 17, 1963. Her death left him consumed by prolonged grief and an obsessive determination to resurrect her through supernatural means. Morisaki possessed extensive knowledge of Agartha, a mythical underworld realm, and believed in the Gate of Life and Death within it, capable of reviving the deceased. To reach Agartha, he commanded the paramilitary group known as the Arch Angels. This group hunted ancient artifacts called clavis crystals, keys needed to access Agartha. At Agartha's entrance, Morisaki and his forces confronted a guardian creature, a Quetzalcoatl. He ordered its killing to proceed, demonstrating his willingness to employ lethal methods for his goal. He manipulated his student, Asuna Watase, to gain her clavis crystal. After entering Agartha, he revealed his true objective: using the Gate of Life and Death to resurrect his wife. During their journey deeper into Agartha, he developed a protective, paternal bond with Asuna. Despite this growing connection, he remained singularly focused on his quest, even when warned repeatedly about the dangers and natural laws governing life and death. Upon reaching the Gate of Life and Death, Morisaki initiated the resurrection ritual for Lisa. The process demanded a severe physical sacrifice, costing him his right eye, and required a living vessel for Lisa's soul, which unintentionally manifested as Asuna. He proceeded with the ritual despite visible anguish and tears, indicating internal conflict over endangering Asuna. The ritual was interrupted when Shin destroyed the clavis crystal, freeing Asuna from possession. Lisa's spirit, before departing, conveyed a final message urging Morisaki to find happiness without her. Emotionally shattered and consumed by guilt, Morisaki requested death from Shin. Shin refused, advising him that carrying the burden of loss was humanity's curse and that he must continue living. Accepting this, Morisaki chose to remain in Agartha permanently while ensuring Asuna returned safely to the surface world.