Known as "Lady" or "Onee-San," this dental clinic assistant in a small town forms a deep bond with a young boy named Aoyama, teaching him chess during her free hours. She possesses a mysterious ability to transform ordinary objects like soda cans into penguins under clear skies, though she initially comprehends neither the origin nor purpose of this power. Environmental conditions dictate its effects: darkness yields bats, while overcast skies prevent any transformation.

Her existence ties intrinsically to "the Ocean," a floating sphere of water discovered in a nearby forest. Distance from the town weakens her, and overusing her penguin-summoning ability induces physical illness. During such episodes, her sweat morphs into hostile Jabberwocks.

Demonstrating consistent concern for others, she frees Aoyama from bullies, deploys penguins to deter subsequent harassment, and comforts him during his own sickness. As the Ocean expands, endangering a research team, her anxiety grows. She collaborates with Aoyama to confront the threat, generating a massive penguin flock to infiltrate the Ocean and rescue the researchers.

To avert the town’s destruction, she must collapse the Ocean. Accepting this necessity, she directs the penguins to dismantle the phenomenon. This act severs her connection to the world. After returning with Aoyama to a local café, she embraces him and vanishes, her ultimate fate unresolved. Her departure embodies the sacrifice made to protect the town and its people.