On a more personal level, Kushina's return could also have an impact on Naruto's relationships. His relationship with his father might change since now both his parents are alive. His friends might view him differently, either with envy or concern. And Kushina herself might have a hard time adjusting to the new world she has been brought back into, which could put a strain on her relationship with Naruto and others.
There might be political consequences as well. The ninja villages could be in an uproar. Some might see Naruto as a threat for going against the natural order. Others might be in awe and try to either use his newfound ability or stop him from using it again. And for Naruto himself, he might have to deal with the guilt of changing something so fundamental, especially if there are unforeseen negative effects on the people around him.
One consequence could be that it messes with the natural balance of the ninja world. Maybe the cycle of life and death is disrupted, and this causes some strange phenomena to occur, like abnormal weather or chakra imbalances.
In certain fanfic ideas, Naruto could have made a deal with some sort of otherworldly being. He might have sacrificed something of great value, like a part of his own chakra or a future ability, in exchange for Kushina's life. Another possibility is that he finds a way to reverse the very nature of death by using some unique properties of the tailed beasts' chakra that he has access to.
She might start by using her knowledge of Naruto's past. Since she is his mother, she knows things about his early life that no one else does. She could use these memories to create an emotional connection with him. Maybe she'll show up in his dreams first, like a hazy memory, and then gradually reveal herself in the real world.
Kushina could also seek the help of other powerful shinobi. For instance, she might ask Minato for assistance. Since Minato was Naruto's father and also a very skilled ninja, together they could come up with a plan to reunite with Naruto. Maybe they would use some sort of space - time ninjutsu to get closer to him.
One consequence could be Naruto's emotional breakdown. Since Kushina is his mother, her betrayal would be a huge blow to him psychologically. He might start to doubt himself and his place in the world.
Naruto would likely be deeply hurt, not just physically but also emotionally. He has always idolized his mother, so an attack from her would be a huge blow to his psyche. His trust in family and those close to him could be severely damaged.
Well, she might face the challenge of Naruto's trust. Since she has been absent for so long, Naruto may not trust her immediately. Also, the ninja world is full of threats. There could be enemies who try to stop her from getting close to Naruto. And Naruto has his own sense of identity which is deeply rooted in being an orphan and a self - made ninja. Kushina has to respect that and find a way to fit into his life without disrupting it completely.
On a more personal level, they could face internal guilt. As Naruto grows up and achieves great things on his own despite their neglect, Minato and Kushina may realize what they've missed out on. This realization could cause them a great deal of internal turmoil and regret for not being there for their son when he needed them.
Maybe they enlist the help of other powerful ninjas. For instance, they could ask Tsunade for medical support in case Naruto is injured. They could also get intel from Shikamaru, who is known for his intelligence. By gathering a team of reliable and strong ninjas, they increase their chances of getting Naruto back successfully.
It's not really possible within the normal Naruto lore. But fanfiction is all about exploring 'what ifs'. In a yaoi fanfiction where Naruto brings Itachi back to life, it could be based on some extreme emotional bond. Maybe Naruto discovers a hidden power within himself that he can use to reverse death. But this goes against the established rules of the Naruto world where death is usually final. So, it's really a matter of the author's creativity and how they can justify such a huge event within the framework of the Naruto world, even if it's a yaoi - inspired take on it.
One possible plot could be that Naruto discovers some ancient and forbidden jutsu. He decides to use it to bring Mito back to life in order to gain more knowledge about the Uzumaki clan. Mito then helps Naruto understand some hidden powers within the clan and they together face a new threat to the village.