Sōseki Natsume is widely considered the foremost Japanese novelist of the Meiji era, and his literary works have served as the source material for numerous anime adaptations, establishing him as a significant original creator in the medium.

Born Natsume Kinnosuke on February 9, 1867, in what is now Tokyo, Natsume came of age during the rapid Westernization of Japan following the Meiji Restoration. He pursued a distinguished academic career, graduating from Tokyo Imperial University with a degree in English literature. He was later sent by the Japanese government to study in London from 1900 to 1902, an experience that profoundly influenced his writing but was personally difficult, marked by poverty and alienation. Upon his return to Japan, he became a lecturer in English literature at Tokyo Imperial University before resigning in 1907 to become a full-time writer for the Asahi Shimbun newspaper. He passed away on December 9, 1916, from complications of a stomach ulcer.

Natsume's literary career produced several landmark novels that are considered classics of Japanese literature and have been directly adapted into anime. His first major success, I Am a Cat, was published serially from 1905 to 1906. This satirical novel is narrated by an anthropomorphized domestic cat who observes and critiques Japanese society, particularly the uneasy mix of Western culture and traditional Japanese values. The novel was adapted into an anime television special that aired in 1982. Another major work, Botchan, was published in 1906 and is a popular, humorous novel based on the author's own experience as a teacher dispatched to a middle school in Matsuyama. The story follows a reckless, morally-driven Tokyo native who clashes with students and corrupt colleagues in the provincial town. Botchan has seen multiple film and television adaptations, including a 1980 anime film with character designs by Monkey Punch, the creator of Lupin III, and a 1986 adaptation as part of the Animated Classics of Japanese Literature series. Natsume's later, more somber novel Kokoro, published in 1914, deals with themes of loneliness, guilt, and the complex relationship between an idealistic young man and an older man he calls Sensei. Kokoro was adapted as episodes seven and eight of the twelve-episode anthology series Aoi Bungaku Series, which aired from October to December 2009. The Aoi Bungaku Series, produced by the animation studio Madhouse, adapted six classic Japanese short stories and novels, presenting them to a modern audience with character designs by notable manga artists.

Recurring themes in Natsume's work, which have carried into their anime adaptations, include a profound sense of alienation, the conflict between individual identity and societal expectations, and the psychological struggle of the modern Japanese intellectual caught between traditional values and Westernization. His early works like I Am a Cat and Botchan are marked by sharp humor and satire, while his later novels, including Kokoro, are notably more somber and introspective, exploring themes of isolation, death, and the search for meaning. His influence on Japanese literature is immense, and his novels remain a staple of the national curriculum, ensuring their enduring legacy. Through anime adaptations, his stories continue to reach new audiences, solidifying his status as a foundational creator whose literary vision transcends his original era.