Summary
Musai serves as a shinobi from Kumogakure. During the Fourth Shinobi World War, he and Nonota fell victim to an ambush by the reincarnated Toroi. Upon realizing his fellow Kumo ninja was the enemy, Musai attempted to warn Nonota about Toroi’s specific techniques, but the attack came before he could finish his sentence. After Nonota became magnetised, Musai continued to explain Toroi’s abilities to him. The pair was subsequently rescued by the arrival of Naruto Uzumaki and Killer B, with Naruto incapacitating Toroi by slamming a Rasengan into him. Musai recounted to his rescuers that they had been en route to Headquarters when they were separated from F and the rest of their group. He was visibly shocked when B revealed that F was actually a transformed White Zetsu. In the anime adaptation, after parting ways with Naruto and B, Musai and Nonota briefly suspected that each other might be White Zetsu impostors as well. However, they quickly realized that the enemy’s goal was to kill them both, confirming they were on the same side. They laughed off the moment, and Musai jokingly pretended to be a transformed White Zetsu, prompting Nonota to defend himself by slashing Musai’s nose with a kunai. Later, Musai and Nonota reunited with their regiment while carrying Toroi. After explaining how Naruto and B had saved them, Torune arrived and summoned a group of Kabuto’s "failures" to retrieve Toroi and the Third Raikage. Among these summoned forces was Musai’s father, Osoi. Musai remarked to a comrade that his father had never managed to pass the chūnin exams, a comment that annoyed Osoi. Before being sealed, Musai promised his father to inform the Raikage that he and Toroi had died fighting for the sake of the village, and they exchanged goodbyes.
