The messenger (waki) of the retired Emperor Takakura delivers an imperial order to Minamoto-no-Nakakuni (shite, historically known as Takashina-no-Nakakuni) to go search for a woman named Kogō-no-Tsubone (tsure). Lady Kogō used to be Emperor Takakura's lover, but fearing the anger of the queen consort's father, Taira-no-Kiyomori, she fled the palace and disappeared. Upon hearing a rumour that she may be hiding in the outskirts of Kyoto, Nakakuni mounts his horse and heads for Sagano to look for Lady Kogō's hideout.
At that time, Lady Kogō (tsure) and her maid (tomo) are hiding in the hamlet of Sagano, living in the house of a local woman (ai). Looking at the autumn moon, overwhelmed with love and hopeless yearning for Emperor Takakura, Lady Kogō takes a koto harp in her hands and plays a song called "Sōburen" ("Thoughts of Love for my Husband") to soothe her heart. Upon hearing the music, Nakakuni is convinced that it is the sound of Lady Kogō's koto harp. He rushes his horse around Sagano to find out where Lady Kogō is hiding. Surprised by Nakakuni's unexpected visit, Lady Kogō tries to hide her identity.
However, realising that Nakakuni cannot be deceived, she finally accepts the letter that Takakura had entrusted to Nakakuni. Lady Kogō narrates famous stories of ancient China about Emperor Wu and Lady Li, as well as the love between Emperor Xuanzong of Tang and Lady Yang Guifei. Convinced yet again of the Emperor's devoted affection, Lady Kogō sheds tears of love and gratitude. Lady Kogō and Nakakuni have a banquet, recalling the good old days. Finally, after performing a dance and expressing his regret to part with the lady, Nakakuni mounts his horse and rides back to the capital.
This Noh play is based on the chapter called "Kogō" in the classic novel "The Tale of the Heike". Although the novel also gives account of the love affairs they've had with others, the Noh play focuses primarily on the love between Emperor Takakura and Lady Kogō, the Lady's disappearance from court and Nakakuni's investigation. Story-wise, this Noh play is very faithful to the novel. In "The Tale of the Heike", Lady Kogō returns to the palace and is even blessed with a daughter from Emperor Takakura. In the end, however, the whole affair comes to the attention of Taira-no-Kiyomori, who forces Lady Kogō to become a Buddhist nun.
What catches the eye in "Kogō" is the stage prop representing a single-wing door. It symbolises the quiet and lonely existence of Lady Kogō. Apart from serving as a landmark to guide Nakakuni, it is also a wall that separates him from the troubled Lady Kogō inside. The scene called "Koma-no-dan", where Nakakuni looks around Sagano under the full moon in mid-autumn, is one of the highlights of the play. The way Nakakuni rides his horse, straining his ears, is beautifully underscored by the gorgeous libretto. The libretto in the scene where Kogō and Nakakuni meet is also exceptionally beautiful.
The love stories of the Chinese emperors mentioned here symbolise the Emperor's love for Kogō. Nakakuni's parting dance is the last element that adds to the autumnal atmosphere of Sagano. This dance, called "otokomai", is usually performed by samurai, but in the case of "Kogō", Nakakuni performs it very gracefully, and at the same time confidently - a dance that adds to the atmosphere of the stage and emphasises the image of Nakakuni as a skilled flutist of refined taste. Lady Kogō's melancholic appearance while seeing off Nakakuni is also one of the most impressive accents of the play.