"Gakkyū-ō Yamazaki" centers on Yamazaki, a fourth-grade student who is notorious for his unruly behavior and academic struggles. Despite his young age, Yamazaki is a self-proclaimed "class king" who believes in asserting dominance through physical strength and intimidation. His antics often disrupt the classroom, creating chaos for his classmates and teachers. However, his life takes an unexpected turn when a new teacher, Mr. Suzuki, arrives at the school. Unlike previous teachers, Mr. Suzuki refuses to tolerate Yamazaki's behavior and challenges him to change his ways.

The narrative explores the dynamic between Yamazaki and Mr. Suzuki, as the teacher employs unconventional methods to reform the troublesome student. Mr. Suzuki's approach involves understanding Yamazaki's underlying insecurities and motivations, rather than simply punishing him. Through a series of confrontations and interactions, Yamazaki begins to question his own behavior and gradually develops a sense of responsibility and self-awareness. The story also delves into the lives of other students in the class, highlighting their individual struggles and how they are affected by Yamazaki's actions.

As the series progresses, Yamazaki's transformation becomes more evident. He starts to form genuine friendships with his classmates and takes on a more positive role within the classroom. The series balances humor with moments of introspection, portraying the challenges of growing up and the impact of mentorship. While Yamazaki's journey is central to the plot, the series also emphasizes the importance of empathy, communication, and mutual respect in overcoming personal and social obstacles. The interactions between students and teachers serve as a reflection of broader themes related to education, discipline, and personal growth.