Inki is a significant supporting character from the anime who serves as an intermediate-level torturer, a position also referred to as a "lieutorment," within the Demon King's army. She first appears near the end of the first episode and later earns a promotion to the rank of "harm-marshal," which is a higher-level torturer position.

Inki is an oni, a type of demon or ogre, distinguished by her fair skin, long lilac hair that often covers the left side of her face, and a single horn with a purple tip. She also possesses a slender devil's tail and typically wears a long black trench coat with sleeves that extend past her hands, a style that reflects her reserved personality. Her posture is often slightly stooped, and she has a calm, quiet presence that contrasts sharply with other more boisterous characters.

Her most defining characteristic is her extreme shyness and anxious nature. Inki is soft-spoken and often stutters, frequently leaving the talking to her more outgoing partner. Despite this timidity, she is deeply thoughtful and self-aware, recognizing that her shy disposition could be an obstacle to her future dreams. She is friendly, kind-hearted, and shows a level of maturity that allows her to prioritize her friendships over her own desires, demonstrating a willingness to sacrifice her own path for the happiness of others.

Inki's primary motivation for becoming a torturer is not rooted in cruelty but in a genuine wish to bring smiles and happiness to others, a desire she has harbored since high school. This unconventional ambition is what initially confuses and then inspires her close companion to join her. Her role in the story is almost always in tandem with her partner and cousin, Youki. Together, they form a formidable duo specializing in combination attacks and cooperative strategies to coax secrets from the captive princess. In addition to her duo tactics, when she works alone, Inki prefers a more gentle and emotional approach to her duties, using shared experiences like watching movies or reading novels to create a bond and subtly persuade her target.

The most significant relationship in Inki's life is with Youki, who is her cousin. The two are nearly inseparable and are often mistaken for twins, though they are simply close relatives. Their bond is one of mutual respect and deep affection, with Inki's quiet demeanor balancing Youki's more energetic personality. Inki also develops a friendly and genuine rapport with the princess, often participating in social activities like trips to theme parks and picnics with her, blurring the lines between captor and captive.

Throughout the series, Inki shows notable personal development, particularly in her professional life. She successfully navigates a promotion exam alongside Youki, demonstrating her competence and determination to advance in her chosen career. This arc shows a young woman actively working to overcome her insecurities to achieve her goal of making others happy through her unique job.

Regarding her abilities, Inki is proficient in what could be called friendship-based or emotional torture. Her tactics rely on creating enjoyable or compelling experiences, such as playing co-op video games or suspenseful movie watching, that the princess finds difficult to resist. She is also exceptionally skilled at video games, particularly strategy and combat genres, and is adept at crane games. While she possesses some combat capabilities, she is not depicted as a front-line fighter, and her skills are notably outclassed by the princess's own abilities.