thumb|upright=1.5|Scene from a long narrative scroll retelling the history of a Buddhist monastery, by [[Tosa Mitsunobu (1434–1535)]] of Japanese painting was founded in the early Muromachi period (14th–15th centuries), and was devoted to yamato-e, paintings specializing in subject matter and techniques derived from ancient Japanese art, as opposed to schools influenced by Chinese art, notably the Kanō school (狩野派). Tosa school paintings are characterised by "areas of flat opaque colour enclosed by simple outlines, where drawing is precise and conventional", with many narrative subjects from Japanese literature and history. However, by the 17th century both Tosa and Kanō artists broadened their range, and the distinction between these and other schools became less clear.
The origins of this school of painting can be traced to (fl. first half 15th century), who first used the professional name of Tosa, though unverified claims to earlier origins were made later by Mitsunobu (1434?–?1525) who formally founded the school. Mitsunobu served as the official painter (edokoro-azukari) at the imperial court, specializing in courtly subjects painted in the yamato-e (やまと絵) style.
The Tosa school under Mitsunobu retained the position of () for three generations, until 1569, and regained the post 1634 under Mitsunori (See #History below). Until the 17th century, the Tosa school painted for the court and aristocratic patrons, which favored such painting subjects as scenes from the classic Tale of Genji (源氏絵), but in later years, the school's range expanded to include bird-and-flower painting and other Chinese-inspired themes and styles. In general, the Tosa style is characterized by rather flat, decorative compositions, fine linework, great attention to detail, and brilliant color.
History
thumb|400px|right|[[Bamboo in the Four Seasons, Muromachi period (1392–1573) Attributed to Tosa Mitsunobu (1434–1535). Pair of six-panel folding screens; color, ink, and gold on paper; 174.3 × 381.6 cm]]It is starting with Tosa Mitsunobu
The earliest documentary evidence for an artist using the name Tosa are two early 15th-century references to a man named Fujiwara Yukihiro (藤原 行広) (fl. 1406–1434) who was also known as Tosa Shōgen (土佐 将監), a title derived from his position as governor of Tosa Province. Yukihiro's activity as a painter is known primarily from an inscription on illustrated handscrolls of the Stories of the Origin of Yūzū Nembutsu (融通念仏縁起); 1414, Seiryōji (清涼寺), Kyoto.
A bloodline descent from Yukimitsu to Mitsunobu (father-son?) is speculated, but the family document lacks records covering that period. The surviving paintings that can be attributed to Mitsunobu show less quality than his reputation in historical sources would suggest, but many fine works remain from Mitsunobu's hand. Although he painted both Buddhist paintings and portraits in addition to the standard repertoire of courtly themes, he is best known for his illustrated handscrolls, emaki (絵巻), such as The Legends of Kiyomizu-dera (清水寺縁起).
thumb|Illustration of the [[Genji Monogatari<br>ch.42 – 匂宮 Niō no Miya ("The Perfumed Prince")<br>Credited to Tosa Mitsuoki (1617–1691).|left]]
The Tosa school's art tradition was passed from Mitsunobu to (1496 – ) under whom the fortunes of the school began to decline, then to , when he moved to the capital with his eldest son, Mitsuoki (光起) (1617–1691) at the invitation of Emperor Go-Mizunoo,
Mitsuoki's successors headed the Imperial painting bureau until the end of the Edo period, but their reliance on imitating the style of Mitsuoki, rather than developing new techniques or themes, led to the production of works that were increasingly static and conventional. However, Mitsusada (1738–1806), a dedicated practitioner of the Tosa traditions, managed to effect a temporary Tosa revival.
Artists of the school but not the family were more significant, notably Sumiyoshi Jokei (1599–1670), a pupil of Mitsuyoshi, and his son Gukei Sumiyoshi (1631–1705), whose work revitalized the original tradition of small narrative scrolls with emphasis on details of everyday life. Reviving interest in Japanese history in the 18th and 19th centuries kept demand for Tosa style work alive, but the style of the school, with its thin line and reliance on detail was less suited to the larger hanging-scrolls that were now the format preferred by patrons. The interest in painting everyday life of the Tosa school was influential on the ukiyo-e school of paintings and prints, especially on the aristocratic painter Iwasa Matabei (1578–1650), who is regarded as one of the founders of ukiyo-e.