Chikako, known by the nickname Chika-chan, recurs across multiple adaptations of the source material, including the film *Himitsu no Akko-chan: Umi da! Obake da!! Natsu Matsuri*. She consistently appears as a young girl who spies on protagonist Akko-chan. Her role centers on observing Akko's activities through eavesdropping and surveillance, frequently triggering comedic moments or advancing the plot. This character maintains her function in the original 1969 anime series, 1988 and 1998 television adaptations, 1989 movie releases, and 2012 live-action film.