In the fanfiction, Naruto may face opposition from within his own village. Some traditionalist shinobi might not understand or accept this new power he's learning. They could see it as a deviation from the established ninja arts. Naruto would then have to deal with not only learning haki but also convincing others that it can be a valuable addition to his arsenal and to Konoha's defenses as a whole.
He might also face challenges in combining haki with his existing jutsu. Since his fighting style is mainly based on ninjutsu, integrating haki into his attacks and defenses without disrupting the balance of his overall combat capabilities would be difficult. He would need to practice a lot to make it seamless, like finding the right moment to use haki - enhanced punches during a taijutsu sequence within a larger ninjutsu - based battle.
One challenge could be controlling it. Haki is a different kind of power compared to chakra, so Naruto would have to learn how to regulate the flow and intensity of his haki. For example, if he uses too much haki at once, it might drain him quickly.
One challenge could be the complexity of the technique itself. Hiraishin is a very advanced ninjutsu, and Naruto might struggle to understand the chakra control required for it.
One challenge could be controlling the natural energy. Since senjutsu involves harnessing natural energy, Naruto might find it difficult to balance it with his own chakra. It's like trying to mix two very different substances without causing an explosion.
One challenge is controlling the amount of nature energy. It's not easy to balance it with his own chakra. Also, Kurama's chakra can be a bit wild, and combining it with senjutsu chakra requires a lot of focus. Another thing is that Naruto has to learn new techniques quickly, which can be mentally taxing.
One challenge could be controlling the chakra flow for creating the marks accurately. Naruto has a large amount of chakra, but it's wild. So, he might find it difficult to precisely form the marks required for Hiraishin.
One challenge could be chakra control. The Lightning Blade requires precise chakra manipulation. Naruto, known for his large and sometimes wild chakra, would need to rein it in. Another might be the physical strain. Using a high - level lightning - based jutsu like this could take a toll on his body.
One challenge could be the physical strain. Flash Step requires a lot of speed and quick movements, which might put a huge stress on Naruto's body. He'd need to build up his stamina and strength to be able to perform it properly.
One challenge could be getting the speed right. Flash Step requires incredible speed, and Naruto, while fast, has to adjust his normal speed to the extreme quickness needed for this technique. Another might be the chakra control. He has to learn how to use just the right amount of chakra to power the Flash Step without overdoing it and exhausting himself.
One challenge could be Naruto's appetite. Naruto loves to eat, so Kakashi would have to constantly find food to satisfy him. Another is Naruto's hyperactivity. Keeping Naruto still and focused on one thing would be tough for Kakashi.
One of the main challenges could be the lack of immediate feedback. When training alone, Naruto doesn't have a partner to correct his mistakes right away. For example, if he's working on a new jutsu, he might not realize he's performing it slightly wrong until it fails completely. Also, he has to motivate himself without the competition or support of his peers. He might get bored or frustrated easily since there's no one around to cheer him on or push him further.
One challenge could be controlling the intensity. Lightning is a very powerful force, and it might be difficult for Harry to rein it in. He could accidentally cause too much destruction when he just wants to create a small spark.