Nemuro has long, straight green hair, usually secured with a prominent purple bow, and large, expressive purple eyes. She dresses in a consistent purple outfit featuring a white collar, cuffs, and hemline, typically paired with white stockings and purple shoes.

Her personality centers on profound lethargy and an intense love of sleep. She often appears drowsy, speaks slowly, and displays a generally apathetic or disinterested attitude towards most activities, opting for rest whenever she can. This laziness translates into reluctance for tasks she finds strenuous or bothersome. Despite this outward drowsiness, she shows loyalty to her companions and can summon surprising focus or determination when sufficiently motivated, especially during critical situations involving the village or her friends.

Her magic specializes in creating, projecting, and manipulating fog and mist. She generates dense fog banks for concealment, shapes mist into defensive barriers or binding tendrils, and uses fog offensively to disorient or overwhelm opponents. She typically invokes her signature spell with the phrase "Nemuri no Kiri wa Nemuro no Mono" (Sleep Mist Belongs to Nemuro). Her magical companion is a purple bat named Komori.

Within her group, Nemuro holds the distinct role of the perpetually sleepy member. Her interactions frequently involve others trying to rouse her or coax her into participation, leading to comedic moments due to her slow reactions and sleep-focused priorities. She maintains close friendships with characters like Hanamaru and Azami, often seen resting near them or participating alongside them, sometimes reluctantly. Her dynamic usually requires encouragement or help to stay awake and engaged.

Across multiple seasons, movies, and OVAs, Nemuro actively participates in defending the village and confronting threats alongside her companions. While her core sleepiness remains a constant source of humor, she proves consistently reliable when situations demand her magical fog abilities. She integrates more deeply into the group's collaborative efforts, showing a willingness to contribute her unique powers despite her natural inclination towards inactivity. Her development is subtle, revealed through increased participation and moments of unexpected alertness or initiative during crucial battles, solidifying her place as a dependable, though perpetually drowsy, team member.