Taira-no-Tsunemasa was the son of Tsunemori, the younger brother of the Taira clan leader Kiyomori. A master of the lute, since an early age he was favoured by the royal prince and Buddhist monk Shukaku-Hosshinnō. The war with the Genji clan compelled him to flee the capital Kyoto. On his way, he decided to drop in at Ninna Temple. He didn't want to take his lute "Seizan" (Blue Mountain) to the battlefield, and instead decided to return it to the royal prince, from whom he had received it as a present. Tsunemasa and Shukaku-Hosshinnō exchanged poems and bid a last farewell to each other. The archdeacon of Ninna Temple, Gyōkei, escorted Tsunemasa to the ridge of Katsura River.
Later, Tsunemasa was slain at the Battle of Ichi-no-Tani ("Tale of the Heike", chapter 7).
The Noh play "Tsunemasa" takes place after these events.
The archdeacon of Ninna Temple, Gyōkei (waki), holds a Buddhist musical service, during which he gives the lute Seizan as an offering to the soul of the deceased Tsunemasa. Later that night, Tsunemasa's ghost (shite) appears before him. Tsunemasa expresses his gratitude for the memorial service, dances and plays music on his treasured lute, Seizan. However, having died with resentment for his enemy in his heart, Tsunemasa has fallen in the Warrior's Hell and cannot help but demonstrate the ceaseless battles he suffers there every day.
Ashamed to be seen in such a wretched state, he blows out the light and disappears.
Seizan is a fabled lute, which is said to have been brought to Japan from China by the 9c aristocrat Fujiwara-no-Sadatoshi together with score which was kept a secret. Since it was a precious and remarkable instrument, people were afraid to even touch it. It eventually came into the possession of Shukaku-Hosshinnō, who in turn bestowed it upon Tsunemasa.
The author of this play is unknown. It is classified as a type two, or a "warrior" play. Such plays usually depict the salvation through Buddhist prayer of the ghosts of warriors who have fallen in the Warrior's Hell and are subjected to the constant torture of having to go through ceaseless battles even in the afterlife.
However, in this particular play, the ghost of Tsunemasa is depicted as a young aristocrat who displays a devotion to the arts through his attachment to the treasured lute. At the end of the play, when Tsunemasa reenacts his tortures in Hell, the usual emphasis on salvation is nowhere to be found - the hero only expresses his shame to be seen in such a wretched state, before blowing out the candles and disappearing.
Even though Tsunemasa unsheathes his sword and frantically moves in circles around the stage at the end, the whole play is imbued with an atmosphere of elegance and refinement. Although short, the play is among the most popular in the repertoire of Noh. The shite actor may use ‘chūjō‘ - a mask typical for the role of a Taira warrior, or ‘jūroku‘ - a mask of a young Taira warrior with a mild expression.
The scene of the play is set in Ninna Temple. For many generations the bishops of Ninna Temple were chosen among members of the Imperial family, and the temple was often referred to as the Omuro Palace. It was a temple for the nobility. Shukaku-Hosshinnō, who favoured Tsunemasa, was the royal bishop of Ninna Temple, making the temple the most adequate place to hold a memorial service for Tsunemasa.
During the play, there is a scene where Tsunemasa plays the lute. However, a prop representing the lute is not provided. Instead, the actor opens a folding fan and, as if embracing it with his left hand, emulates the movements of playing the lute.