Ryoutarou Iwanaga is a Japanese manga artist known for creating the long-running series Pumpkin Scissors. He was born in Hyogo Prefecture and began his professional career in 2002. Prior to his mainstream debut, he worked under the pen name Iwao Nishinari, creating adult manga. His first major serialized work, and the work for which he is best known, is Pumpkin Scissors, which began publication in 2002 in Kodansha's Magazine GREAT. The series later moved to Monthly Shonen Magazine in November 2006, where it continued for many years.

The story of Pumpkin Scissors is set in an empire recovering from a devastating war, focusing on a unit dedicated to post-conflict reconstruction and disaster relief. The narrative explores the social scars left by war, including famine, disease, and class stratification, following the members of the Imperial Army State Section III, known as the Pumpkin Scissors unit. The series is noted for its focus on a postwar setting rather than the war itself, dealing with themes of poverty, inequality, and the lingering effects of violence on a society.

Ryoutarou Iwanaga is credited as the original creator and sole author of Pumpkin Scissors, responsible for both the story and the artwork. His work on the series led to its adaptation into a twenty-four episode anime television series, which aired from October 2006 to March 2007. For this adaptation, he is credited as the original creator. The manga has been released internationally in multiple languages, with over twenty-three collected volumes published in Japan as of March 2024. English editions have been published by Kodansha Comics. The series is categorized as a shonen manga, aimed at a young adult and adult audience.

Throughout his career, Iwanaga has remained largely defined by his commitment to this single, expansive narrative. He has a reputation for meticulous work on dialogue and scene composition, referred to as name in the manga industry. He has reportedly shared insights into his creative process and struggles with maintaining the quality of the entertainment he produces. His artistic identity is tied to a grounded, realistic tone within a fictional military setting, avoiding heavy fantasy or mecha elements in favor of a more personal and socially conscious drama. In the industry, he is recognized as the creator of a long-running title that has sustained a dedicated readership and an anime adaptation, marking a significant contribution to the military and drama genres in manga.