Nagabe is the professional pseudonym of Ayumu Yoshida, a Japanese manga artist and illustrator born on August 1, 1993, in Tokyo. He developed an interest in drawing from a young age, initially copying characters from popular manga. During middle school, he began creating his own original characters, frequently incorporating animal ears and other anthropomorphic features, which were a growing trend at the time. He later graduated from the Visual Arts program at Musashino Art University.

Nagabe's professional career began when a publisher discovered his illustrations on the online art community Pixiv. This led to his first commercial work, Buchou wa Onee, published in 2013 by Akane Shinsha. His career gained significant momentum in 2015 when he began serializing his most famous work, The Girl from the Other Side: Siúil, a Rún, with the publisher Mag Garden.

The Girl from the Other Side is a dark fantasy manga set in a divided world where a young human girl named Shiva lives with a cursed, non-human figure known only as Teacher, who cannot touch her without causing harm. The series concluded in Japan in March 2021. Its success led to multiple adaptations. A short anime film, produced by Wit Studio and Production I.G, premiered in August 2019. This was followed by a full-length theatrical anime adaptation, The Girl from the Other Side, which was released in 2022.

Beyond this flagship title, Nagabe has created numerous other manga series, often exploring different genres while maintaining a distinctive artistic identity. These works include The Wize Wize Beasts of the Wizarding Wizdoms, Monotone Blue, and Love on the Other Side. Many of his stories, particularly those outside of The Girl from the Other Side universe, incorporate Boys' Love themes.

Recurring themes in Nagabe's work include the use of anthropomorphism, a focus on communication across barriers of language and species, self-acceptance, and the exploration of same-sex relationships. He has stated that the central theme of The Girl from the Other Side is "gentleness," which he explores through the core limitation that the two protagonists cannot touch each other. His artistic style is notably influenced by Western illustrators and authors. He has frequently cited Tove Jansson, creator of the Moomin series, as a major inspiration for his graphic style and use of hatching techniques. Other influences include the American illustrator Tasha Tudor and the Spanish comic series Blacksad.

Nagabe is recognized for his unique position in the manga industry as a largely self-taught artist who never worked as a traditional manga assistant. His success with a distinctive, non-canonical style has made him a notable figure in alternative manga, and he was an honored guest at the 2018 Salon du Livre book fair in Paris.