Junko Ejima teaches class 3-2, instructing students like Dai and Eren. She possesses long blue hair tied just below the neck, a slim build, and average height. Her signature outfit includes white heels, long white stockings, a red skirt, and a pink shirt topped with a light yellow apron. She also wears a light yellow dress featuring orange accents paired with matching white heels. Her undergarments appear in various styles, including plain white, blue with yellow star patterns, and pink with flower designs.

Her personality blends kindness and compassion with pronounced irritability, especially triggered by Dai Daichi's persistent skirt-lifting. She physically reacts, knocking Dai away and sighing in frustration. Though she declines Dai's gifts, she exhibits a degree of tolerance for his behavior. Professionally enthusiastic, she uses expressive gestures during storytelling to engage her students. However, she struggles with empathy and interpersonal interpretation, often weaving exaggerated narratives from minor incidents. This tendency extends to adult relationships, revealing a certain naivety.

A key narrative involves her anonymous online friendship with Mamoru Daichi, another individual facing social difficulties; neither recognizes the other's real identity. Dai's skirt-lifting serves as a recurring comedic device, explicitly referencing the character Miss Machiko.

In the special episode "Into the Depths of Marital Hell," she visits the Amber Crystal simulation game park with Mamoru. Mamoru adopts a knight avatar to gain experience points while Junko participates within the game's scenarios. Their visit coincides with a space monster invasion at the park, though her specific actions during this conflict remain undefined.