Futaroh Yamada is the pen name of Seiya Yamada, a Japanese author born on January 4, 1922, in Hyogo Prefecture. He graduated from the faculty of medicine at Tokyo University but embarked on a literary career after his mystery short story The Incident on the Dharma Pass won a prize from the magazine Houseki in 1947. He was discovered by the renowned mystery writer Edogawa Rampo and went on to become a novelist of significant repute, active until his death on July 28, 2001.

While Yamada was a novelist and not a manga artist, he is a pivotal original creator in the world of anime and manga due to his extensive Ninpōchō (Ninja Scrolls) series of novels. These historical fantasy novels, which blend ninja lore with action and often supernatural elements, have served as the source material for a vast number of adaptations across film, television, and especially manga and anime. Among his most notable works in this series is The Kouga Ninja Scrolls, a 1959 novel that was adapted into a highly successful manga titled Basilisk by artist Masaki Segawa from 2003 to 2004, which subsequently inspired a popular anime series in 2005. The manga adaptation of Basilisk won the Kodansha Manga Award for general manga in 2004.

The example cited, The Yagyu Ninja Scrolls, follows a similar pattern. It is a manga series illustrated by Masaki Segawa, based on Yamada’s 1964 novel Yagyū Ninpōchō, which is the first installment in his Yagyū Jūbei trilogy. The manga was serialized in Kodansha’s Weekly Young Magazine from 2005 to 2008 and was later published in English by Del Rey Manga. This pattern of adaptation is consistent across Yamada’s bibliography; other novels in his ninja series, such as Iga Ninpōchō, Kunoichi Ninpōchō, and Makai Tenshō (also known as Ninja Resurrection), have similarly been adapted into manga and anime.

Yamada’s work is characterized by a recurring thematic focus on ninja, their secret techniques (ninpō), and intricate plots often set during the early Edo or Sengoku periods of Japanese history. His stories frequently feature conflict between rival clans, supernatural martial arts, and complex revenge narratives, which have proven to be rich material for adaptation. Beyond his ninja novels, Yamada was a versatile writer who produced mystery stories, historical crime fiction, and even a Sherlock Holmes pastiche, demonstrating a broad range within popular fiction. His significance to the industry lies in his role as a foundational source creator; his novels provided the narrative core for numerous successful manga and anime titles that have reached audiences worldwide.