Height: 165 cm (5'5")
Weight: 53 kg (116 lbs)
Starsign: Capricorn (stated in the anime by Jinta, her birthday was not revealed though)

Naruko is a childhood friend of Jinta and Menma. While she displays a cold attitude towards Jinta, she is secretly concerned for him. She is perhaps the closest to him at present and is enrolled the same school (although Jinta stopped attending school). Chiriko comments that Naruko has not changed over the years: she is still easily persuaded by everyone around her. Naruko seems to be popular in high school and gets along well with girls that Chiriko deems "sluts."

While they have grown apart, Naruko seems to care deeply about her childhood friends. She works at a video game store and has a large collection of manga and video games herself. Because of this collection, she started reconnecting with Jinta and Poppo.

Naruko admits that, when she was a child, she was jealous of Menma. Insecure of her glasses and curly hair, she desperately wanted to have flowing hair like Menma. Moreover, she was jealous of Jinta's affection towards Menma. Naruko secretly had a crush on Jinta, which is why she asked him whether he had feelings for Menma. She blames herself for Menma's death, because her question ultimately precipitated in Menma's death. Presently, it is shown that Naruko still has lingering feelings for Jinta.

Naruko is involved in a scandal when an older boy, whom she was hanging out with, tries to force her into a love hotel. When she wouldn't agree to have sex with him, he attempts to force her into the hotel to rape her; however, Matsuyuki protects her. Despite this, the rumor that Naruko had sex with this man reaches her high school. Naruko has to face the judgments of her fellow students until she decides to stop going to school in favor of working full-time to get the money to build the rocket.

She feels slighted when Jinta focuses on Menma and continues to ignore her, even after they reunited. Matsuyuki, who feels similarly since Menma is denying him, asks Naruko out. However she later tells Chiriko on the bridge that she loves only Jinta and that he is irreplaceable.