Isoda Koryūsai (礒田 湖龍斎, 1735–1790) was a Japanese ukiyo-e print designer and painter active from 1769 to 1790.

Koryūsai was born in 1735 and worked as a samurai in the service of the Tsuchiya clan. He became a masterless rōnin after the death of the head of the clan and moved to Edo (modern Tokyo) where he settled near Ryōgoku Bridge in the Yagenbori area. He became a print designer there under the art name Haruhiro in 1769, at first making samurai-themed designs. The ukiyo-e print master Harunobu died in 1770, and about that time Koryūsai began making prints in a similar style of life in the pleasure districts.^[1]

Koryūsai was a prolific designer of individual prints and print series,^[1] most of which appeared between 1769 and 1881.^[2]

In 1782 Koryūsai applied for and received the Buddhist honour hokkyō ("Bridge of the Law")^[1] from the imperial court^[3] and thereafter used the title as part of his signature. His output slowed from this time, though he continued to design prints until his death in 1790.^[1]

Koryūsai's known designs total 2500, or an average of four a week. According to art historian Allen Hockley, "Koryūsai may ... have been the most productive artist of the eighteenth century".^[2]

The series Models for Fashion: New Designs as Fresh Young Leaves (Hinagata wakana no hatsumoyō, 1776–81) ran for 140 prints, the longest ukiyo-e print series of beauties known. He designed at least 350 hashira-e pillar prints, numerous kachō-e bird-and-flower prints, a great number of shunga erotic prints, and others.^[1] 90 of his nikuhitsu-ga paintings are known, making him one of the most productive painters of the period.^[2]

Despite the Koryūsai's productivity and popularity—both in his time and amongst later collectors—his work has attracted little scholarship.^[4] The first ukiyo-e histories written in the West in the 19th century elevated certain artists as examplars; Koryūsai work came to be seen as too indebted to Harunobu, who died in 1770, and inferior to Kiyonaga, whose peak period came in the 1880s.^[3] An example is Woldemar von Seidlitz's Geschichte des japanischen Farbenholzschnittes ("History of Japanese colour prints", 1897), the most popular of the early ukiyo-e histories, which paints Koryūsai as a successor to Harunobu and a rival of Kiyonaga's in the 1770s who slipped into mediocrity and imitation of his rival by the end of the decade.^[5] Interest lay mainly in the details of Koryūsai's life—a samurai who received court honours was unusual in the proletarian world of ukiyo-e.^[3] In 2021, contemporary woodblock printmaker David Bull created a series of 12 prints depicting nature scenes adapted from Koryūsai's designs.^[6][7]

His work is held in the permanent collections of several museums worldwide, including the British Museum,^[8] the Museum of Fine Arts, Boston,^[9] the Carnegie Museum of Art,^[10] the Princeton University Art Museum,^[11] the Minneapolis Institute of Art,^[12] the University of Michigan Museum of Art,^[13] the Hermitage Museum,^[14] the Suntory Museum of Art,^[15] the Israel Museum,^[16] the Krannert Art Museum,^[17] the Los Angeles County Museum of Art,^[18] the Philadelphia Museum of Art,^[19] the Honolulu Museum of Art,^[20] the Museum of New Zealand,^[21] the Brooklyn Museum,^[22] the Ashmolean Museum,^[23] the Fine Arts Museum of San Francisco,^[24] the Freer Gallery of Art,^[25] the Indianapolis Museum of Art,^[26] the Chazen Museum of Art,^[27] the Portland Art Museum,^[28] and the Kimbell Art Museum.^[29]