Kuu is a peculiar young girl dwelling within a surreal dimension. She initiates contact with Shin, a boy from another world, by summoning him into her own. This interdimensional summoning unwittingly sparks the destabilization and ultimate explosion of her dimension.

Her interactions with Shin form a significant narrative focus. Described as quirky and strange, she initially forges a bond with him, sharing moments of companionship. However, her demeanor abruptly turns cold when she decides to sever their connection, declaring a sudden aversion to Shin. This rejection deeply wounds him, fueling his emotional distress.

After rejecting Shin, Kuu chooses to abandon her dimension entirely. Her departure coincides with Shin's desperate attempt to reach her, resulting in a bicycle crash. During this event, the accumulated emotional fallout—originating from her summoning, their subsequent bond, and her rejection—materializes as a cataclysmic explosion of their shared reality. This explosion unfolds through abstract visuals and transformations, signifying the release of pent-up emotions and the shattering of their connection.

Kuu's background or origins remain unexplored beyond these events. Her character serves as the primary catalyst for the dimension's destruction and Shin's emotional journey, her actions directly driving the surreal conflict.