"Black-Haired Kerry and the Casebook of Romantic Troubles" centers on Kerry, a high school student with a unique ability to see the "romantic troubles" of others as physical manifestations. These troubles appear as strange, often comical creatures that latch onto individuals, representing their unresolved romantic issues. Kerry, despite her own lack of experience in love, becomes an unofficial advisor to her classmates, helping them confront and resolve these problems.

The narrative unfolds episodically, with each chapter focusing on a different character and their romantic dilemma. Kerry’s sharp intuition and empathetic nature allow her to identify the root causes of these troubles, which often stem from miscommunication, unrequited feelings, or personal insecurities. As she assists her peers, Kerry’s own understanding of love and relationships gradually deepens, though she remains somewhat detached from her own romantic prospects.

Key characters include Kerry’s best friend, who often provides emotional support and comic relief, and a mysterious classmate who harbors a secret connection to the origins of Kerry’s ability. The series balances lighthearted humor with moments of genuine emotional insight, exploring themes of self-discovery, vulnerability, and the complexities of human connections. The episodic structure allows for a diverse range of romantic scenarios, from first crushes to long-standing misunderstandings, making the series relatable to a broad audience.