Well, Naruto's friends' reactions would be a mix of shock, excitement, and concern. Hinata would be very worried about Naruto's safety, but also proud of him for achieving such a powerful form. Kiba might make some jokes about Naruto looking like a blue-haired weirdo at first, but deep down he would be impressed. Shino would be observing Naruto's new form quietly, analyzing how it could affect the dynamics within the group and the overall strength of the village.
His friends' reactions would be diverse. Kakashi would be proud yet cautious. He would encourage Naruto to master the form but also remind him of the great responsibility that comes with such power. Choji might be a bit in awe and ask Naruto if he can still eat ramen like he used to. Ino would be excited and might try to get Naruto to show off his new powers more often, while also being concerned about the potential danger it could bring to Naruto and the village.
Sasuke would probably be both intrigued and a bit competitive. He might see Naruto's new form as a challenge and start to train harder himself to keep up. Sakura would be amazed at first, but then worry about the risks Naruto might be taking with this new, untested power. Shikamaru would be thinking about the implications it has for the village and how they can use Naruto's new form to their advantage.
In the fanfiction, Naruto's Super Saiyan 4 form could have some unique Naruto - style twists. His traditional ninja outfit might be modified to fit the new, more powerful form. Maybe it would be more form - fitting and have some red and gold accents to match the Super Saiyan 4 color scheme. Also, his whisker - like marks could become more prominent or even glow in this form. His overall appearance would be a blend of the fierce Super Saiyan 4 look and his own ninja identity.
Sasuke might be initially suspicious. Given their complex relationship, Sasuke would likely want to know the real reason behind Naruto's identity change. But once he understands the motives, he might respect Naruto's decision if it's for a good cause.
Naruto's character could develop a sense of pride that he didn't have before. This Super Saiyan 3 form is something extraordinary, and he might start to show it off a bit. But at the same time, he would also have to learn humility. If he becomes too arrogant, his friends might distance themselves from him. So he would be in a constant struggle between showing off his power and being the humble ninja he was raised to be. Also, his leadership skills might improve as he now has a power that others look up to, and he would need to lead by example when it comes to using this power responsibly.
Naruto might become more confident, bordering on cocky at times. The Super Saiyan 4 transformation comes with a lot of power, and with that power, he could start to believe he's invincible. But deep down, his core values of protecting his friends and the village would still remain. He might also become a bit more impatient, as the power coursing through him could make him eager to jump into battles quickly.
Shikamaru, being the intelligent one, would try to analyze the situation first. He would understand that Naruto isn't himself and would start to plan a way to reverse whatever happened. He might try to gather the other ninja to form a strategy. Kakashi would be deeply disappointed. He has trained Naruto and seen his growth, and this change would be like all his efforts going to waste. He would try to talk to Naruto, using their past experiences to try and break through to the real Naruto inside.
Sakura would probably be very angry at first. She'd likely try to find out the truth immediately and would not rest until she clears Naruto's name. She might use her medical ninjutsu skills to get into the jail if needed.
His other friends like Shikamaru would be in shock. Shikamaru, who is usually calm and collected, would struggle to come to terms with Naruto's death. They would all have to deal with the loss of the village's hero and a great friend, and it would likely change the dynamics of the entire group.
Naruto would probably be very excited and want to immediately start making changes for the better. He has always been about hope and improvement.
I think Naruto's friends would be quite shocked. For the more traditional ninja like Neji (if he were still alive in this fanfic), he would see the gun as an abomination to the ninja way. However, Naruto's closest friends like Kiba would be more open - minded. Kiba might see it as a cool new weapon and want to see what it can do. But overall, they would all be concerned about how Naruto got the gun and what it means for their world of ninjas.
As for Shikamaru, he would probably find the whole situation too troublesome. He might avoid 'female Naruto' at first, but then when he realizes it's really Naruto, he would start to give advice on how to handle the situation in the most efficient way, like how to avoid unwanted attention from other guys.