She idolized Rei Hino and wanted to become a priestess just like her. To fulfill this dream, Nanako followed Rei around and did everything just like her, but when she overheard Rei making disdainful comments about her (wrongfully thinking that Nanako was following her because she had no life), she became upset.
When she was leaving the shrine in tears, Nanako was attacked by VesVes for her Dream Mirror, but it turned out to be a blank. The Lemures of the day, ManeMane Musume, started mocking Nanako in front of the Sailor Guardians, revealing that she was insecure under her bubbliness. The weakened Nanako tearfully begged the monster to stop, which touched Sailor Mars' heart and she discovered her new power, Mars Flame Sniper. After she was saved by the Sailor Guardians Nanako found a real dream to follow: to work as a waitress in a café, which made her very popular.