Another of Chika's good friends in high school. She considers Chika to be her chief rival and is often jealous of the love-love relationship that she and Chizuru assume Chika to have with Kaoru. She is about the only person who can beat Chika at swimming besides Tina Foster (who nicknames her "Nakki").

In bonus chapters to manga volumes 15 and 16 we see that Natsuki has a budding girlfriend:boyfriend relationship with a neighbor boy, and that she works part time in a flower shop.