After the chaos of a busy school day, Natsumi goes on an odyssey throughout the city.

After a day of battling monsters and aliens, Natsumi arrives home to hear a story about an apocalyptic future in which she, Ongo, and Ahem band together to destroy a dangerous monster.

Visiting a hotspring, Natsumi must intervene when the spring's administrator is possessed by an evil force. And...once again, Natsumi must rescue her companions.