Musai is a shinobi from Kumogakure. He's best known for his involvement during the Fourth Shinobi World War, where he and his teammate Nonota found themselves in serious trouble against a reincarnated enemy.
The two got ambushed by Toroi, a fellow Cloud Village shinobi who'd been brought back as a reincarnated fighter. Musai tried to warn Nonota about Toroi's techniques, but things went south fast—Nonota got magnetized before Musai could finish explaining. Fortunately, Naruto Uzumaki and Killer B showed up and bailed them out, with Naruto hitting Toroi hard with a Rasengan.
After the fight, things got weird. B revealed that their teammate F was actually a White Zetsu in disguise the whole time. This freaked out both Musai and Nonota, who started eyeing each other suspiciously, wondering if one of them might be a fake too. Once they realized the enemy had tried killing both of them, they relaxed—same side, after all. They laughed it off, though Musai's attempt to joke around by pretending to be a White Zetsu didn't land well. Nonota slashed his nose with a kunai before Musai could finish the bit.
Later, while carrying the defeated Toroi back to their regiment, things took an emotional turn. Torune showed up with some of Kabuto's failed experiments, including Musai's own father, Osoi. Musai had always been frustrated that his old man never made it past chūnin rank, much to Osoi's annoyance. Before his father got sealed away, they said goodbye—Musai promised to tell the Raikage that he and Toroi had died fighting for the village.
Manga Debut: Chapter #546
Anime Debut: Naruto Shippuuden Episode #296
Content compiled by AnimeList.moe from publicly available sources.
