There could also be new characters introduced. For example, a young apprentice that Naruto takes under his wing. This character could be someone who Naruto discovers has a hidden potential for the shinobi arts, and he decides to train them in the hope of reviving the shinobi world. Or maybe there's a mysterious figure who is the cause of Naruto being the last shinobi, and this figure would be a major character as well.
Obviously Naruto is one of the main characters since it's in the title. He is likely to be the central focus of the story as the last shinobi.
Sasuke might also be a main character. Even if Naruto is the last shinobi in some sense, Sasuke could be involved in the story, perhaps as an ally or someone with his own agenda related to Naruto's situation. They have a long - standing relationship in the Naruto universe, so it's likely he would play an important role.
A practical answer is Chapter 120, because it turns the idea into a concrete scene. The chapter opens with Facing the sudden and somewhat strange request from Jiang Li, Director Sun..., adds pressure through Netizen: Wen Jiaojiao had been acting for years without much fame, but now..., and ends on.
Look to Chapter 139 for the clearest answer. It begins with Wen Jiaojiao's live stream was inundated with a wave of question marks., keeps building through Princess Wen, what are you doing?, and lands on The audience in the live stream didn't know about Wen Jiaojiao's inner....
The best chapter pointer here is Chapter 200, "Only Two Points?!". It opens with Shang dismissed the thought of turning around and walking away. and closes on Are you doing this on purpose?" Zhao Lang instantly put on an innocent....
If you want the clearest chapter reference, go to Chapter 179. Early on, Everyone originally had no expectations for the gifts that Su Yinwan...; later, the chapter leans on Although they felt there might be a catch, a few people still curiously....
A practical answer is Chapter 153, because it turns the idea into a concrete scene. The chapter opens with Wisps of smoke gradually rose from the small kitchen., adds pressure through But the next second, Jiang Li looked up, with a sincere face she said,..., and ends on After leaning in, he saw.
Chapter 163 is the strongest chapter-level answer because it starts from Su Yinwan entered a small room, guided by a staff member. and follows through on Moreover, by doing so, the online viewers would think her more innocent....
Chapter 190 is the strongest chapter-level answer because it starts from Several people who didn't understand fell silent. and follows through on Because he saw the pack of cigarettes pinched between Jiang Li's fingers..
Chapter 159 is the strongest chapter-level answer because it starts from Seeing the red light of the camera turn on, Su Yinwan looked at the... and follows through on Shang Shaobai, who was browsing through files, received a call from his....