In 'naruto's hypnotic harem fanfic', Naruto is surely a main character. In addition to him, depending on how the author writes it, it could be that some of his friends or allies are involved. For example, Tenten might be one of the characters in the harem. Also, some of the antagonists' female subordinates could also be part of the harem. So characters like Anko might also be main characters in this particular fanfic, but it really depends on the creativity of the fanfic writer.
Since it's a Naruto - based fanfic, Naruto would likely be one of the main characters. And probably some female characters from the Naruto series like Sakura, Hinata, or other female ninjas could be part of the harem and thus main characters in this fanfic as well.
The main character is Naruto, no doubt. As for the harem part, it could include a diverse range of characters. There could be the kunoichi from his own village like Ino, who might be part of the harem. Then there could be characters from other villages as well. Maybe a female shinobi from the Sand Village like Temari could also be involved. And don't forget about some of the minor female characters in the Naruto world who could be added to the harem in this fanfic, which would then make them main characters in the context of this particular story.
A practical answer is Chapter 8, because it turns the idea into a concrete scene. The chapter opens with The resentment that had barely calmed among the crowd surged back two..., adds pressure through Why keep harping on the fact that he wasn't a decent man?, and ends on Other people with a.
The best chapter pointer here is Chapter 3, "Madam, the eldest young master has been missing for over half a month". It opens with Qiao was still annoyed at the attitude of this unknown girl when she heard... and closes on Jiang Yan, forced into a marriage with someone he did not love, had....
A practical answer is Chapter 13, because it turns the idea into a concrete scene. The chapter opens with Sensing that something was off with Jiang Yan, Jiang Yan dismissed the..., adds pressure through He probably had a good guess who it was., and ends on How could this happen..." Lin Manru.
Look to Chapter 39 for the clearest answer. It begins with Qi Tianyu had been looking forward to watching Jiang Li's drama unfold., keeps building through But to his surprise, Wen Jiaojiao, who seemed to possess some strength,..., and lands on His original intention was just to make Jiang Li back.
Chapter 866, "Why don't you die in his place?!", is the clearest early answer because it turns Didn's situation into a concrete plot event. The chapter gives readers a real answer by opening on In Shuiyun Temple, Changqing silently watched everything happening in...
Chapter 791, "There's Actually a Suona?!", is the clearest early answer because it turns Chen Taifan's situation into a concrete plot event. The chapter turns that into something concrete by moving from The lights in the audience suddenly went out, and immediately, the...
Chapter 835, "Is this your way of handling things? So pathetic.", is the clearest early answer because it turns Mommy's situation into a concrete plot event.
Chapter 836, "It's been a long time since I last saw Jin Siyue", is the clearest early answer because it turns Zhao Lang's situation into a concrete plot event. The chapter gives readers a real answer by opening on You!" Rong Junsheng seemed to have heard the commotion over here and...
If you want the clearest chapter reference, go to Chapter 2. Early on, On the top floor of the Financial Building, a gathering of dark clouds...; later, the chapter leans on How dare Jiang Li hang up his phone?.
If you want the clearest chapter reference, go to Chapter 11. Early on, After a meeting, Shang Shaojing pinched the bridge of his nose, tired, and...; later, the chapter leans on How is it going with the Jiang Family?" The assistant looked troubled and....