Naruto would probably first try to fight back. He's not the type to just go along with being kidnapped. He'd likely use his Shadow Clone Jutsu to create a distraction and try to escape.
At first, Naruto would be angry and defiant. He has friends and a village to protect, and being kidnapped would be seen as an obstacle to that. However, as he gets to know Kohana better during the 'kidnapping' situation, he might start to understand her point of view and even try to help her if he feels she's in some sort of trouble herself.
Sakura would be extremely worried. She would probably try to gather the other members of Team 7, like Sasuke and Kakashi, to go after them. Sasuke might be a bit more hesitant at first, but his loyalty to Naruto would eventually make him join the search. Kakashi, on the other hand, would be more strategic. He would try to figure out Minato's motives first and then plan the rescue mission accordingly.
Well, one possible plot twist could be that Kohana has a hidden motive that's not as evil as it seems at first. Maybe she's being controlled by a greater force and Naruto realizes this and tries to save her instead of just escaping. Another could be that Kohana is actually from a long - lost clan that has a prophecy related to Naruto, and the 'kidnapping' is a way to start fulfilling that prophecy.
Regular Naruto fanfiction usually follows the general themes and moral compass of the original series. But 'evil Kohana Naruto fanfiction' takes a turn. It flips the idea of Kohana being a place of good. In regular fanfic, we expect the village to be a positive force, but in this type, it's often the source of problems.
At first, Naruto would be completely shocked. He has always seen Hinata as a loyal friend and someone who has deep feelings for him. So the idea of her betrayal would be hard to fathom. He might try to deny it at first.
He would be filled with rage. Naruto has a strong sense of justice and the fact that someone took Hinata away from him would fuel his anger. He would vow to find and punish whoever was responsible. He might even become reckless in his pursuit of vengeance, endangering himself and those around him. His friends would have to step in to try and bring him back to his senses.
Naruto would probably be heartbroken. He loves Hinata deeply, so finding out she might have cheated would shatter him.
He could also feel angry. After all, he has fought for his friends and the village. To be betrayed by someone like Sirzechs would make him want to prove his innocence. He might start training even harder to show that he is not the bad guy Sirzechs is making him out to be. And he would likely try to find evidence to clear his name.
Naruto would be extremely hurt. He's a very emotional person who values friendship deeply. He'd probably first try to understand why Yugao did it. He might be in denial at first, thinking it's some kind of misunderstanding.
Naruto would be determined to get to the bottom of it. He would not just accept the betrayal at face value. He would use his skills and the help of his friends to investigate what made Jiraiya turn against him. Naruto's ninja way is about never giving up, and this situation would be no different. He would fight against this betrayal, both physically if Jiraiya became an enemy in combat, and emotionally, trying to understand the reasons behind it all while still holding on to the hope that Jiraiya could be redeemed.
Naruto would probably be really confused at first. He respects Kurenai, so he'd be hesitant to fight back right away. He might try to talk to her and ask what's wrong.