Hajime Ichinose is a rather eccentric schoolgirl who is obsessed with notebooks. One day, she is approached by a mysterious man named JJ who pulls out a journal called a NOTE from her body, declaring her to be the new member of the elusive Gatchaman team. She later follows the words appearing in her NOTE to the mall, where a Gatchaman named Sugane Tachibana manages to defeat an alien that had disguised herself as a human. Later that day, Sugane brings Hajime to the Gatchaman's hideout where she meets the other members, Jou Hibiki, O.D., Utsu-tsu, and their leader, Paiman. Sugane explains that their duty is to protect Earth from a hostile alien race known as the MESS. Hajime and Sugane are soon called upon by JJ to fight a MESS at the bus station, during which Hajime transforms for the first time, whilst a mysterious figure watches.