Kokin-chan, a germ-character from the Anpanman franchise, is consistently recognized as Dokin-chan's younger sister. She first arrives on Earth inside a transport egg but later gains recurring mobility through a personal UFO crafted by Baikinman. Visually, she appears as a bright blue germ with a red bow on her antenna, teal shoes, and white hands, maintaining this design across appearances. Her personality is extremely greedy and self-centered, driving her to act on personal desires while ignoring others' feelings, instructions, or social norms. This trait frequently fuels jealousy and conflict with her sister, though a laid-back side emerges in the Miitopia spin-off.

Her signature ability involves generating artificial blue tears. Physical contact with these tears forces victims into uncontrollable, unexplained crying, immobilizing them. This power disrupts both heroes like Anpanman and villains like Baikinman, serving as both defense and chaos.

Narrative origins differ: the 2006 short film *Kokin-chan and the Blue Tears* shows her egg-based arrival resembling Baikinman and Dokin-chan, with her tears causing widespread distress until Dokin-chan calms her. Alternatively, her debut in the *Sore Ike! Anpanman* series depicts her transport egg crashing onto Baikinman during an attack on Anpanman.

Later stories integrate her into the world. Character-focused DVD compilations feature her in comedic or heartwarming interactions with entities like the Lamp Giant, Bikubik-chan, or the Den-Den Troupe. The 2014 short *Tanoshiku Teasobi Mama ni Natta Kokin-chan!?* sees her discovering an egg that hatches into a caterpillar, Tefutefu, which imprints on her as its mother, compelling her to provide temporary care.

Initially an episodic visitor, she evolves into a recurring figure after obtaining her UFO, regularly engaging with Anpanman's cast. Merchandise and subsequent media occasionally depict improved relations with Dokin-chan, contrasting earlier sibling rivalry.