Dokin-chan is a germ-like alien from another planet, serving as Baikinman's primary partner in crime. She typically assists him in schemes to cause trouble or defeat Anpanman, though her own motivations often differ from his destructive aims. Her germ species design features an orange-red body, a white face with green eyes, small red cheeks and nose, pink shoes, white hands, a single antenna, and a long tail similar to other germ characters.

Her personality is selfish, greedy, and demanding, marked by a childish demeanor. She frequently bosses Baikinman around, compelling him to fetch food, objects, or capture individuals. Despite this, she occasionally displays underlying kindness, particularly in her intense, obsessive romantic infatuation with Shokupanman. This crush drives independent actions like elaborate attempts to lure him into traps or engineer romantic encounters. Her room is filled with Shokupanman posters and plush toys, and she frequently daydreams about him, though her advances remain unreciprocated.

She maintains a complex dynamic with Baikinman, exploiting his loneliness and vulnerability to serve her whims—even sending him into danger—while also showing concealed care. Her loyalty is conditional, often abandoning confrontations at the first sign of failure. Her relationship with younger sister Kokin-chan involves sibling rivalry and conflict, worsened by their shared crush on Shokupanman. They occasionally cooperate but frequently squabble or compete.

Dokin-chan possesses an enchanted dual-pointed staff capable of enlarging or shrinking objects upon contact. She also utilizes a pink UFO with yellow hands for transportation and occasionally for hostage-taking, though it more commonly carries items like flowers or baskets.

In *Yōsei Rinrin no Himitsu*, she joins Baikinman's scheme involving the fairy Rin-Rin, supporting his villainous plans while prioritizing her personal desires, especially those concerning Shokupanman. The English dub of this film refers to her as "Dokeen". Her alien background from a non-humanoid species is occasionally referenced, though details about her origins are sparse. Her name, "Dokin," incorporates the Japanese onomatopoeia "doki" (a rapidly beating heart), reflecting her excitable nature and romantic pursuits. She remains a comedic antagonist across official media, with occasional vulnerability or kindness not altering her fundamental alignment or behavior patterns.