Mysterious and kimono-clad, Kiku emerges in an otherworldly realm after a traffic accident, intercepting the protagonist’s passage into a memoryless afterlife. She steers them through the realm’s rules, stressing the need to secure a train ticket and reignite their suppressed longing to return home.

Her identity intertwines with the protagonist’s past, unveiled as the narrative unfolds: she embodies "Kii," their former pet fish, anchoring their bond in shared history. This truth surfaces during fragmented memory retrieval at a bureaucratic lost-and-found counter, where a stern station attendant and Mrs. Mori, a goddess-like overseer, help reconstruct the protagonist’s fractured self.

Kiku guides the protagonist through trials imposed by the realm’s rule-bound guardian, her resolve blending steadfast optimism with pragmatic acceptance of the world’s rigid logic. A childhood friend’s astral projection occasionally aids their mission, though this thread chiefly resolves practical barriers rather than enriching Kiku’s own arc.

Her purpose centers on propelling the protagonist toward emotional reckoning, urging them to confront buried regrets to reclaim their humanity. She personifies themes of memory’s fragility and the perils of evasion, persistently challenging avoidance. Her existence remains bound to her role as guide and transformed companion, a steadfast catalyst for awakening buried truths.