"Mirmo Zibang!" centers on the life of Kaede Minami, a middle school girl who struggles with loneliness and unrequited love. Her life takes a fantastical turn when she discovers a magical teapot containing Mirmo, a mischievous and energetic fairy from the fairy world. Mirmo is a "matchmaker fairy" tasked with granting Kaede's wishes, but his methods often lead to chaotic and humorous situations. The fairy world, known as Molmol, is a whimsical realm filled with magical creatures and rules that often clash with the human world.

Kaede's primary wish is to win the affection of her crush, Aoi Yamada, a kind and popular boy in her class. Mirmo, along with his fairy companions—Rima, Murumo, and Yashima—attempts to help Kaede navigate her romantic and social challenges. However, Mirmo's impulsive nature and the interference of rival fairies, such as the scheming Ganko and her minions, frequently complicate matters. The series explores themes of friendship, self-confidence, and the complexities of young love, blending magical elements with everyday school life.

The narrative is episodic, with each episode presenting a new challenge or wish that Kaede and Mirmo must tackle together. The dynamic between Kaede and Mirmo evolves as they learn to trust and understand each other, despite their differences. The series also delves into the fairy world's politics and Mirmo's backstory, revealing his reasons for becoming a matchmaker fairy and his relationships with other Molmol inhabitants. Through its mix of comedy, romance, and fantasy, "Mirmo Zibang!" offers a lighthearted yet engaging exploration of human emotions and the power of connection.