Ran Musen attends Inspiration Academy Private High School, an institution for geniuses. Her extraordinary computer programming skills enable her to hack government satellites and virtually any system, reflecting her name's meaning, "wireless LAN."

Initially, Ran despises protagonist Taketo Akutagawa, branding him a "porno writer" for his erotic fiction specialty. She consistently blames him for misfortunes and reacts with physical violence, standing as his most vocal detractor.

Romantically and physically, Ran pursues female classmates exclusively. She subdues Botan Beni with a kiss, shares intimate sleepovers with peers, and in an OVA, restrains Tsukuru Kagaku while removing most of her clothing to molest her. She also "had a taste" of Fukune Narukara.

Ran's hostility toward Taketo shifts after he rescues Fukune from Botan Beni. This prompts her to reassess him, evolving into friendship. By the series' end, she becomes one of his closer allies, though she occasionally reverts to violence against him.

Physically, Ran has blue hair styled in a ponytail and rosy cheeks. She wears Inspiration Academy's standard female uniform.