Mimirin Midorihara is an anthropomorphic snowshoe hare with white fur, long ears featuring pink inner ears and black tips, a forehead tuft, a pink nose, and a visible buck tooth. A signature pink ribbon sits near her left ear, replacing an initial flower earring. Her attire evolved from a yellow puffy-sleeved shirt with a red overall dress to a pink top and cyan skirt, and now features a polka-dotted grey dress paired with a pink cardigan; seasonal variations introduce lighter fabrics and accessories like sunhats.

She lives on Challenge Island, where her family runs Flower Shop Midorihara. Her personality blends gentleness, naivety, and liveliness with occasional spoiled, clumsy, and crybaby tendencies. She makes friends readily but harbors fears of snakes, caterpillars, and insects. Despite her species, she dislikes carrots, favoring strawberry shortcake, dolls, and flowers. Her aptitude for racing makes her the fastest among her peers. She aspires to become a princess, florist, or nurse.

Relationships form a core part of her background. She is a childhood friend of Ramurin, who gifted her the signature ribbon before departing. Other kindergarten friends include Shimajiro Shimano, whom she helped overcome shyness, Torippii Sorano, Nyakkii Momoyama, Marurin Sasaki, Kikko Hayashida, and Sakurako Koinuma, emphasizing mutual support.

Her name reflects Japanese origins: "Midorihara" combines "green" (緑, midori) and "fields" (原, hara), while "Mimirin" incorporates "ears" (耳, mimi) and "dignified" (凛, rin).

She appears in multiple franchise films: *Eiga Shimajirō Mahō no Shima no Daibōken* (2018), performing in the ending theme "Happy Jam Jam"; *Miracle Island's Rainbow Carnation* (2024); and the upcoming *Shimajiro and the Song of Courage* (2025), featuring adventures involving magical quests, emotional growth, and supporting characters like Miley in gaining confidence.