Ryō Koshino is a Japanese manga artist born in September 1967 in Sanjo, located in Niigata Prefecture. He began his journey in the manga industry after winning the Morning Shiki prize in 1987. Following his university education, he initially worked at an advertising agency before leaving that position in 1994 to become an assistant to manga creator Akira Oze, pursuing a professional career as a manga author.

Koshino made his serialization debut in 2004 with the medical drama Ns'Aoi (also known as Ns'Aoi Those Days), which was published in Kodansha's Weekly Morning magazine and ran until 2010, spanning 32 collected volumes. This work was later adapted into a Japanese television drama in 2006. Between 2008 and 2009, while still working on Ns'Aoi, he simultaneously published Toshi Advisor Ariko (Investment Advisor Ariko) in Kadokawa's Comic Charge magazine, for which he provided the artwork.

One of his notable original works is Machiisha Jumbo!!, known in English as Town Doctor Jumbo!!. This slice of life medical comedy seinen manga was serialized in Kodansha's Shuukan Gendai magazine from December 2010 to March 2015 and was compiled into 16 volumes. The series was adapted into a live-action Japanese television drama that aired in 2013.

Following the conclusion of Town Doctor Jumbo!!, Koshino launched Dr. Ashura, a medical manga published in Nihon Bungeisha's Weekly Manga Goraku beginning in 2015. The series was released in France by Komikku Editions across four volumes between April. Ashura centers on Shura Anno, a talented and relentless doctor at a second-tier hospital whose near-superhuman surgical skills earn her the nickname Ashura, after the multi-armed Buddhist deity.

Koshino's body of work demonstrates a sustained focus on medical themes, with several of his major series exploring the lives, challenges, and ethical dilemmas faced by healthcare professionals. The medical setting recurs across Ns'Aoi, Town Doctor Jumbo!!, and Dr. Ashura, establishing this as a consistent element of his artistic identity as a creator of seinen manga aimed at adult readers. His more recent work includes Bounce Back, a sports manga centered on golf, which began serialization in Kodansha's Shuukan Gendai magazine in 2020. Koshino has also created other series such as Hana Uta, which was serialized in a publication of the Japanese Nursing Association, and Ginko Gaido Tanto Tanaka Haruo. In September 2023, an exhibition titled When the Words Draw was held in Nantes, France, showcasing his original artwork and his connection to his hometown of Niigata, indicating his growing international recognition.