Suzune Hizuki begins as Naoto Rindo's fiancée, tied to a spiritual family tradition requiring Naoto to father a son with one of the Hizuki sisters to inherit his family company. A car accident strikes just as Suzune prepares to confess her love to Naoto, plunging her into a coma. Her soul lingers within a toy ring Naoto once gave her. When her younger sister Ayumi wears this ring, Suzune's soul possesses Ayumi's body, enabling interaction while Suzune's own body remains comatose.

To revive Suzune, Naoto and Ayumi undertake an intimate ritual involving sexual intercourse aimed at conceiving a child, believed necessary to restore Suzune to her original body. The original storyline concludes with Suzune deceased after the accident, leading Naoto to marry Ayumi. However, an alternate or sequel narrative diverges: Suzune survives the accident and ultimately marries Naoto alongside Ayumi in a polygamous relationship. This version features her active participation in the central romantic dynamic.

Her arc explores the fallout from the accident, her spiritual connection to the ring, and the resurrection efforts. The resolution differs between narratives, with the alternate outcome incorporating her survival and direct inclusion within the familial structure.