School of painters, founded by the 16th-century artist Unkoku Tōgan 雲谷等顔 (1547-1618), who considered themselves to be in the lineage of Sesshū Tōyō 雪舟等楊 (1420-1506).
Tōgan was a native of western Japan and a retainer for the Mōri 毛利 family, who lived in what is now Yamaguchi Prefecture. Tōgan first studied Kano painting methods *Kano-ha 狩野派 in Kyoto. Toward the end of the 16th century, however, Tōgan's patron Mōri Terumoto 毛利輝元 (1553-1625) installed him at the Unkokuan 雲谷庵, Sesshū's former studio in Suō 周防 Province (now Yamaguchi Prefecture). Tōgan was able to study the great landscape scroll Sansui chōkan 山水長巻 by Sesshū in the Mōri collection, carefully copying it and adding an inscription to the original in 1593. Adopting brush work and themes of the master, Tōgan called himself "the grandson of Sesshū," and appropriated the name of Sesshū's studio for his artistic name.
Tōgan worked primarily in Kyoto, although he maintained ties with several monastic institutions in the Kyoto area which were supported by his patrons in western Japan. He painted principally in monochrome ink, often on screens. Representative of his work is *Chikurin shichiken 竹林七賢 (The Seven Sages of the Bamboo Grove) and other paintings at the Ōbaiin 黄梅院 in Daitokuji 大徳寺, built in 1588, Kyoto. These representative paintings from the Ōbaiin, along with other works such as that in the Museum of Fine Arts, Boston, affirm his indebtedness to Sesshū while showing a personal approach to landscape.
Tōgan's elder son, Tōoku 等屋 (d. 1615?) remained in Yamaguchi, but died early. His work is relatively unknown, as is that of several later followers. However, another son Tōeki 等益 (d. 1644), who called himself the fourth-generation Sesshū, collaborated with his father on a number of projects both around Kyoto and in Yamaguchi. On his father's death, he succeeded to Tōgan's position as official painter to the Mōri family. Like his father, Tōeki received the title hokkyō 法橋.
Tōeki and his sons continued the Unkoku school in the 17th and early 18th centuries, bringing to traditional painting themes a combination of Kano school colorist techniques with ink-painting techniques which characterize their school. The school inevitably lost creative momentum by relying on stylistic and uncompositional stereotypes but nevertheless lasted into the 19th century. Paintings of the school are primarily ink landscapes suiboku sansuiga 水墨山水画, but a number of ink and color bird-and-flower paintings also exist.