"Handa-kun" is a comedic slice-of-life anime that serves as a prequel to "Barakamon," focusing on the high school life of Seishu Handa, a talented but socially awkward calligrapher. The series is set in a high school where Handa is a second-year student, revered by his peers for his artistic skills and perceived aloofness. However, Handa’s introverted nature and lack of social awareness lead to frequent misunderstandings, causing his classmates to misinterpret his actions as acts of rebellion or profound wisdom. This results in Handa unintentionally gaining a reputation as a delinquent, with many students idolizing or fearing him.

The narrative revolves around Handa’s daily interactions with his classmates and the absurd situations that arise from their misconceptions. Key characters include Rei Ichinose, a cheerful and overly enthusiastic student who becomes Handa’s self-proclaimed best friend despite Handa’s reluctance; Junichi Aizawa, a delinquent who initially views Handa as a rival but later becomes one of his admirers; and Yukio Kondou, a quiet and observant classmate who often provides deadpan commentary on the chaos surrounding Handa. Other notable characters include Tsutsui, a teacher who is overly invested in Handa’s life, and Akane Todoroki, a popular girl who harbors a crush on Handa but struggles to express her feelings due to his obliviousness.

The series is episodic, with each episode presenting a new scenario where Handa’s actions are misinterpreted, leading to comedic outcomes. Despite his desire for a quiet and uneventful school life, Handa constantly finds himself at the center of attention, often to his dismay. The humor stems from the contrast between Handa’s genuine intentions and the exaggerated reactions of those around him, creating a lighthearted and often absurd atmosphere. While the story primarily focuses on comedy, it occasionally touches on themes of friendship, self-perception, and the challenges of communication, offering a glimpse into Handa’s character before the events of "Barakamon."