The shogun Minamoto no Yoritomo has ordered that samurai from various provinces gather at the foot of Mt. Fuji, where he will hold a hunting competition. The Soga Brothers, Jūrō Sukenari and Gorō Tokimune are on their way there, with a plan to kill Kudō Suketsune, their father’s murderer. As they reach Mt. Fuji, the brothers decide to attack Suketsune at night. First, they ask their retainers Danzaburō and Oniō to bring keepsakes back to their mother who stayed back home. However, the two retainers are reluctant to obey the order. Torn between the warrior’s duty to pursue vengeance until the end and the retainer’s obligation to follow the master’s orders, the two try to commit suicide. The Soga brothers stop them, reminding them that no one would be able to report to their mother of the attack against Suketsune. Understanding that, Danzaburō and Oniō receive a letter and a keepsake from the Soga brothers, then leave.
As night falls, a Ōtōnai, a Shinto priest serving Suketsune, escapes from the fight. He recounts how the Soga Brothers attacked and killed Suketsune.
The Soga Brothers attack but are met by many enemy warriors, among whom Furuya Gorō and Gosho Gorōmaru. Soga Gorō is ready for what could be his last battle. Gorō’s elder brother, Jūrō, is killed. Gorō now stands alone against his enemies. He strikes Furuya, but is pinned down by Gosho, who was disguised as a woman, and is taken in front of the shogun.
The story of the Soga Brothers’ revenge appears in the martial chronicle Soga Monogatari. The Soga Brothers, Jūrō Sukenari and Gorō Tokimune, and their quest to avenge their father’s death has been depicted in numerous plays of various performing arts.
In addition to Youchi Soga, there are several other nō plays based on the same subject, among which Chōbuku Soga, Genpuku Soga, Kosode Soga, and Zenji Soga. Youchi Soga portrays the final act of their revenge plan. However, the scene in which the Brothers confront their sworn enemy, Kudō Suketsune, is not shown in the play. Instead, the killing of Suketsune is recounted by the servant Ōtōnai in the comic interlude between the two acts. The play structure emphasizes the first act, in which the retainers Danzaburō and Oniō part from the Soga Brothers emphasizing the ethics binding parents and children, as well as lords and retainers.