"Kuromajyo-san ga Tōru!!" is a comedic anime series that revolves around the daily life of Chiyo, a high school girl who becomes entangled with a quirky and eccentric witch named Kuromajo. Kuromajo, whose real name is Gorgeous, is a self-proclaimed "black witch" who arrives in the human world to complete her training. She chooses Chiyo as her assistant, much to Chiyo's initial dismay, and the two form an unlikely partnership.

The narrative primarily focuses on the humorous and often chaotic situations that arise as Kuromajo attempts to master her magical abilities while navigating the mundane world. Despite her grandiose claims of being a powerful witch, Kuromajo frequently bungles her spells, leading to unintended and comical consequences. Chiyo, who is practical and level-headed, often finds herself cleaning up the messes caused by Kuromajo's magical mishaps.

Throughout the series, Kuromajo and Chiyo encounter various magical and supernatural entities, including other witches, spirits, and mythical creatures. These encounters often serve as the basis for episodic adventures, blending elements of fantasy with slice-of-life comedy. Despite their differences, the bond between Chiyo and Kuromajo grows stronger as they face challenges together, with Chiyo gradually becoming more accepting of her role as Kuromajo's assistant.

The supporting cast includes characters such as Chiyo's classmates and family members, who occasionally become involved in the magical chaos. Kuromajo's familiar, a talking black cat named Kuro, also plays a significant role, often providing sarcastic commentary and assisting in magical endeavors.

The series maintains a lighthearted tone, with humor derived from the contrast between Kuromajo's over-the-top personality and Chiyo's grounded demeanor. The episodic structure allows for a variety of comedic scenarios, ranging from magical duels to everyday school life, all while exploring themes of friendship, perseverance, and the absurdity of blending the magical with the ordinary.