Yasuda Tomoharu, lord of the Shinano province (Nagano prefecture), was killed by his cousin Mochizuki Akinaga over a dispute. His retainer, Ozawa Tomofusa, left Shinano and retreated to the village of Moriyama, in the Ōmi province (Shiga prefecture), where he now keeps an inn. Fearing for their lives, Tomoharu’s wife and their son, Hanawaka also escaped Shinano, and are now wandering from village to village, seeking for shelter. One day they reach Tomofusa’s inn. He is surprised to meet the family of his former lord. The three rejoice in this unexpected reunion, and Tomofusa swears loyalty to the heir of his lord, Hanawaka.
All the more unexpectedly, Mochizuki, Tomoharu’s killer, and his servant also reach Tomofusa’s inn. They are on their way back to Shinano from the Capital. There, Mochizuki underwent trial for the murder of Tomoharu but was declared not guilty. Now he and his servant have come to the inn to spend the night. Mochizuki wants to keep his identity hidden, but his servant inadvertently reveals his name to Tomofusa.
Amazed at this unforeseen event, Tomofusa and Hanawaka see a chance to avenge Tomoharu, and devise a plot to assassinate Mochizuki: Tomofusa will get him drunk, while Hanawaka and his mother will entertain him with music and dance. The mother sings, and Hanawaka performs a kakko dance, beating on a small drum. After Mochizuki’s request, Tomofusa performs a shishi-mai (lion dance).
Soon Mochizuki falls asleep. Tomofusa and Hanawaka declare their identity and launch the attack stabbing him to death. Now that revenge is done, Tomofusa, Hanawaka and his mother can return to their home in Shinano.
Mochizuki offers numerous points of interest, from the realistic acting of the first part, in which the characters meet at the inn, to the dances of the second part, featuring various songs and dances.
In the party scene Hanawaka’s mother acts the role of a blind female storyteller, singing an episode from the Soga Monogatari, the epic tale of two brothers seeking to avenge the death of their father. Listening to the tale, Hanawaka hears the words “let’s strike!” and mistakes this for the signal to attack his enemy. Tomofusa stops the boy before it is too late while Mochizuki reaches for his sword.
In order to perform the “lion dance”, Tomofusa covers his face with a red cloth and wears two golden fans representing the fangs of a lion, surmounted by a red wig. This dynamic dance, featuring stamps and jumps, is also performed in the noh Shakkyō, in which the main characters are mythical lions. However, the version performed in Mochizuki is different: during the dance Tomofusa moves close to Mochizuki and stamps his feet, ascertaining that he is asleep. Finally, in the fight scene, the actor performing Mochizuki exits the stage leaving his hat behind, thus symbolizing that he is dead.