Prince Semimaru (tsure), Emperor Daigo’s fourth son, was born blind. Now that he has grown into a young man, his father ordered that he be exiled to the woods on Mt. Ōsaka (between Kyoto and Shiga prefectures). Riding on a palanquin, Semimaru is taken to the mountain by the Imperial retainer Kiyotsura (waki). There, Kiyotsura shaves Semimaru’s head, initiating him into Buddhist priesthood. Finally, Kiyotsura departs, leaving Semimaru alone, his dear biwa (a kind of lute) as the only companion.
There appears Hakuga no sanmi (ai-kyōgen). Pitying Semimaru, he leads him a straw hut and promises to help him in case of need.
Back in the city, Semimaru’s elder sister, Sakagami (shite) has become distraught. Her hair grows upwards, a signal of her emotional state. She has left the Imperial Palace and has started wandering aimless. Soon, she reaches Mt. Ōsaka.
As it started raining, and Semimaru plays the biwa and recites poems to comfort himself. Wandering through the woods, Sakagami hears the elegant sound of a biwa and is drawn to it. She finds the hut where Semimaru is living. Recognizing each other, brother and sister rejoice in this fateful meeting, and reminisce about their life at court. Sakagami laments her aimless wandering and pities Semimaru for the condition in which he has fallen. After promising that they will meet again, Sakagami leaves. The two call on each other, until their voices fade into the distance.
Prince Semimaru is not a historical character, but a literary invention appearing in a well-known poem in the “Hyakunin isshū” collection. His sister Sakagami, too, is a fictional character. She is depicted as a free but troubled spirit is reflected in her disheveled hair.
Soon after appearing, Sakagami dances the “kakeri” sequence, characterized by an irregular tempo which expresses her emotional instability. Later, in the “michiyuki” sequence, Sakagami describes her travels from Kyoto to Mt. Ōsaka. Looking down at a stream flowing nearby, she sees her image mirrored in the water. Both Semimaru and his sister suffer for some kind of discrimination due to their physical or mental condition, for which they now live in an “upside-down” world.
Though the authorship of the play is uncertain, it is thought it was performed at the time of Zeami (1363-1446).