"My Little Sister Can Read Kanji" is set in a future Japan where the language and culture have undergone significant changes. The story revolves around Gai Odaira, a young man living in a society where classical Japanese literature and kanji have become nearly obsolete. In this world, modern Japanese has evolved into a simplified form, and the ability to read and understand traditional kanji is a rare and highly valued skill. Gai’s younger sister, Kuroha Odaira, possesses an extraordinary talent for reading and interpreting classical texts, making her a prodigy in this new cultural landscape.

The narrative explores the dynamics between Gai and Kuroha as they navigate their roles in this linguistically transformed society. Gai, who aspires to be a writer, struggles with the limitations of the modern language and feels overshadowed by his sister’s abilities. Kuroha, on the other hand, is deeply passionate about classical literature and often uses her knowledge to challenge societal norms and inspire those around her. Their relationship is central to the story, blending elements of sibling rivalry, admiration, and mutual support.

As the plot unfolds, the siblings become involved in various literary and cultural endeavors, often encountering eccentric characters who represent different facets of this futuristic Japan. These include scholars, writers, and enthusiasts of classical literature, each contributing to the exploration of how language shapes identity and culture. The series delves into themes of tradition versus modernity, the preservation of cultural heritage, and the power of language to connect people across generations.

The story is structured around episodic adventures that often involve deciphering ancient texts, solving literary mysteries, or engaging in intellectual debates. Through these experiences, Gai and Kuroha grow both individually and as siblings, learning to appreciate their unique strengths and the value of their shared passion for literature. The series balances humor, drama, and philosophical reflection, offering a nuanced portrayal of a world where the past and present collide in unexpected ways.