Well, Naruto is a really strong - willed character. So, at first he'd be really hurt. But then, he would probably try to figure out why his family has forgotten him. He might go on a journey to find answers, all the while dealing with the pain of this rejection. He could also be angry at his family for forgetting him so easily, especially considering all he's been through.
At first, Naruto would likely be very confused and hurt. He has always craved family love and acceptance, so this sudden turn would be a huge blow. He might try to plead with his family, asking them to believe him and give him a chance to explain.
Naruto would probably be really hurt at first. He's always been someone who values his friends and to be forgotten on his birthday would sting. He might try to hide his disappointment though, putting on a brave face.
Initially, Naruto would be in shock. He'd try to talk to his friends like Sasuke or Sakura, but when they look at him with blank stares, it would break his heart. He would feel like an outsider in his own village. But then, his ninja spirit would kick in. He would start investigating. He might think it has something to do with a new enemy or some hidden plot. He'd be on a mission to not only get his friends and family to remember him but also to protect the village from whatever threat caused this forgetting in the first place.
Shikamaru, being the laid - back yet perceptive friend, would probably think that Naruto has a plan. He would be concerned but also understand that Naruto is not one to make hasty decisions without a good reason. He might keep an eye on Naruto's family in his absence and hope that Naruto will return safely one day.
His father, Minato, could be a likely candidate in a really dark fanfiction. Maybe he was resurrected in an imperfect way and his mind was warped, causing him to turn on Naruto.
His friends would likely be shocked. Shikamaru, for example, would probably be disappointed in Sakura. He might try to comfort Naruto and tell him to think rationally. Choji might be angry on Naruto's behalf and want to confront Sakura. And Sasuke, if he's around, might have a complex reaction. He might feel a strange sense of satisfaction that Naruto is finally seeing Sakura's 'true' side, but also a bit of pity for Naruto.
Some of Naruto's friends could be really enthusiastic about his new friendship with Tora. Choji might offer Tora some of his favorite snacks. Ino could try to dress Tora up in cute little outfits. However, Neji might be a bit skeptical at first, thinking that Tora could be a distraction for Naruto. But as he sees the positive impact on Naruto, he would come around.
Sakura might be a bit hesitant at first. She's always seen Naruto as the go - lucky, friendly guy. But she would eventually support him if she saw that his intentions were good and that the empire was built on positive values like justice and equality. Sasuke, on the other hand, would be more cynical. He might suspect Naruto's motives initially, thinking it could lead to dictatorship. But after seeing Naruto's actions, he could become one of his closest advisors, using his own experiences to help Naruto avoid making mistakes. Shikamaru would be involved in the strategic planning. He would be both excited and worried about the whole idea, constantly thinking about the long - term consequences.
Sakura might be very worried. She's a medical ninja, so she would be concerned about the potential harm Naruto could be doing to himself. She'd probably try to stop him or at least monitor his experiments closely. Sasuke, on the other hand, might be more understanding in a way. He knows what it's like to push oneself for power, but he might also be a bit skeptical and warn Naruto about the risks.