Perhaps one of the Kiri's high - ranking officials who believes that Naruto's growing influence in the ninja world could be a threat to Kiri's future. So he orders the kidnapping in the name of protecting Kiri. This official may think that by studying Naruto or using him as a bargaining chip, he can secure Kiri's position among the other ninja villages.
There might be a secret organization within Kiri that operates in the shadows. They kidnap Naruto because they think he holds the key to some ancient prophecy that could change the balance of power in the ninja world. They are fanatical about achieving their goals and see Naruto as the means to an end, regardless of the fact that it could lead to war between Konoha and Kiri.
It could be a rogue ninja from Kiri who has his own motives for kidnapping Naruto. Maybe he wants to use Naruto's power to take over Kiri. He sees Naruto as a tool to gain control and doesn't care about the consequences for the relations between Konoha and Kiri.
The story could start with Naruto being lured into a trap set by Kiri. Once kidnapped, he finds himself in a prison cell deep within Kiri's territory. The Kiri ninjas might try to interrogate him about Konoha's secrets or his own unique abilities. Naruto, being Naruto, refuses to cooperate. As time passes, he befriends a fellow captive who has some knowledge about Kiri's inner workings. With this new ally, Naruto formulates a plan to break free. Meanwhile, Konoha's search party is facing many obstacles in their attempt to find Naruto in the unfamiliar and dangerous land of Kiri.
It could be a power - hungry shinobi within Kiri. This shinobi might see the Sage as a threat to his own rise in the village hierarchy. So, he uses his influence to keep the Sage neglected and also tries to sabotage any attempts by the Sage to gain recognition.
Well, Naruto is obviously one of the main characters. There might also be some original Kiri - nin characters created specifically for this fanfiction. For example, a young and talented Kiri - nin who becomes Naruto's friend or rival.
The main characters could be a combination of well - known Naruto characters and new ones made for the fanfic. Maybe a Kiri shinobi could be a main character, someone with a unique backstory and abilities. It could also have characters from other villages who come to Kiri for some reason, like a joint mission or to seek refuge. And of course, there might be some antagonist characters within the Kiri village who create conflict for the protagonists.
It's hard to say for sure without reading it. But it could be some well - known Naruto characters like Zabuza or Kisame who are from Kiri and might have a connection to the monster. Maybe there are also some original characters created specifically for this fanfiction.
The main antagonist could be Shere Khan. He has always been a threat to Mowgli and might see kidnapping him as a way to finally get rid of the 'man - cub'. He could be working with some of his sly jackal minions to carry out the kidnapping.
It could be a young and ambitious Kiri ninja who has grown up seeing the neglect of his village. He might be determined to change the situation and prove that Kiri is not to be underestimated. Maybe he has a special jutsu or ability that he believes can put Kiri back on the map.
Kakuzu might also be a main antagonist in this fanfiction. He's always after money and power. Maybe he sees Sakura as a valuable asset, either to sell her back to Konoha for a large sum or to use her skills for his own gain. He's not very empathetic and would likely be ruthless in his treatment of her.
In this fanfiction, there might be a Kiri - native ninja who discovers Naruto when he's just a child and takes him in. This character would be an important one, as they would be the one to introduce Naruto to the ways of Kiri. Also, there could be a group of anti - Naruto shinobi in Kiri who see him as a threat to the village's traditions and try to drive him out. They would be antagonists in the story.
However, there could be a group in Kiri who are more open - minded. They might be curious about Naruto and his abilities. They could welcome him and even offer to train with him, sharing their unique water - based jutsu knowledge in exchange for his knowledge of Konoha's techniques.