The play Sugawara denju tenarai kagami (Mirror of learning & transmitting Sugawara's secrets of calligraphy: 菅原伝授手習鑑) is based on legends surrounding the life of Sugawara Michizane (845-903: 菅原道真), also known as Kan Shôjô (菅丞相). Founder of the Kanke school of calligraphy and a favorite of Emperor Daigo, Sugawara ran afoul of an envious political rival named Fujiwara no Tokihira (Fujiwara no Shihei in the play) and was exiled to Kyûshû. After Sugawara's death, plague and drought spread throughout Japan and the sons of Emperor Daigo died in succession. The Imperial Palace's Great Audience Hall was struck repeatedly by lightning, igniting fires, and Kyoto was battered by rainstorms and floods. Attributing these calamities to Sugawara's vengeful spirit, the imperial court built and dedicated to him a Shinto shrine in 986 called Kitano Tenmangu (北野天満宮) in Kyoto. The court also posthumously restored his title and office, and removed records of his exile. Sugawara was deified as a Tenjin (Heavenly [Sky] deity: 天神), and many Shinto shrines in Japan were and continue to be dedicated to him.
In the stage drama, Sugawara is a calligraphy master and Minister of the Right who shares power with Shihei, Minister of the Left. Sugawara is arrested on a trumped-up charge of plotting to overthrow the emperor and becomes the target of an assassination plot headed by Shihei. Sugawara is exiled to Kyûshû, where he dies cursing Shihei. Ultimately, the villain is slain by the calligrapher's son, Kan Shûsei, the house of Sugawara restored, and Sugawara pronounced a deity.
Two of the protagonists in this triptych are featured in one of the most popular and frequently performed scenes from the play. Kan Shôjô decides to pass on his secrets to his former disciple Takebe Genzô who has been banished from the court for falling in love with a lady-in-waiting named Tonami. After Kan Shojô is exiled, Genzô and Tonami take Kan Shôjô's son, Kan Shûsai, with them to a provincial school they have established in order to keep him safe from Shihei's intrigues. Later, in Act IV, the Terakoya ("Temple School": 寺子屋) scene, Genzô and Tonami must sacrifice an innocent boy to save their master's son. The boy lives and, many years later, avenges his father's exile and death by slaying Shihei.
Another impression of the complete triptych is in the Museum of Fine Arts, Boston (Acc #11.35164-6).
References: WAS-IV, no. 296 (center sheet only)