Midori Kodama, nicknamed "Jidama," is a central character. Her nickname stems from an alternate pronunciation of the kanji in her surname, Kodama, used by close friends. She is an 11-year-old fifth-grade student in Class 2 at Minami Elementary School.

Jidama lives with her grandmother, Haru. They share a close relationship despite occasional conflicts, exemplified by Jidama once running away to Azuki's bedroom after a disagreement, which underscores underlying tensions but also their strong bond and mutual understanding. Her mother, Aoi Kodama, is a nurse who rarely appears, primarily in episode 102. Aoi's demanding career creates challenges in balancing work and parenting, leading to periods of unintended neglect and a complex mother-daughter dynamic.

The Kodama family names reflect spring and natural hues: "Midori" means "green," "Aoi" means "blue," and "Haru" means "spring."

Personality-wise, Jidama is tomboyish, assertive, and physically confident. Her aggressive tendencies contribute to a "No Guy Wants an Amazon" perception among some male characters. She initially disliked her given name, similar to Azuki's early aversion to her own nickname. Jidama consistently favors practical clothing like kiddy coveralls or overalls, avoiding dresses except during formal occasions like wearing traditional girls' kimonos.

Her interpersonal relationships include membership in Azuki's friend group, where they form the "Club of Unreturned Love" to discuss romantic frustrations. A notable standalone episode involves Jidama confronting a thief who breaks into her home; the thief's face remains vivid in her memory afterward.