Noriko Nishimura is a timid fourth-grade student who dreams of becoming an idol star. She loves fashionable clothes and is easily embarrassed by her younger brother, Hiroto. During the group's summer camp, she often acts as the voice of reason when her peers Natsuki and Amane argue.

Her decision to attend the camp was spurred by a crush on the oldest boy, Kiyoshi Sato. While focused on Kiyoshi, she shows little interest in other camp activities. Her first meeting with Pochi, the talking alien dog, is so shocking she faints.

Later, needing money for their cosmic journey, Noriko works alongside Kiyoshi as an office assistant. Compared to the others, she often stays in the background. However, at a critical moment in the climax, she surprises everyone. Noriko punches a major antagonist while shouting "I'm strong too!", revealing unexpected assertiveness that helps secure the group's success.

Information about her family life or personal history beyond her relationships with Hiroto and Kiyoshi remains unspecified.