When something like the Rasengan becomes so intertwined and integral to the story like it has been, I’m often left wondering if Kishimoto Masashi planned this from the very beginning or if it was an idea that developed along the way. Seeing as the Rasengan was first seen over seven years ago (way back in chapter 150), I’m leaning heavily towards the latter possibility though. Given the nature of the business, I’d say there’s a very slim chance a mangaka would plan seven years ahead with full expectation that their manga will be running that long. Regardless, the revelation that Minato’s idea behind the Rasengan came from the Jinchuuriki’s Imari 「威鞠」 ability works well in my eyes, plus it ties into the overarching subplot that a lot of things were left behind with Naruto’s future in mind. If nothing else, it also gives off a fairy tale-like vibe, which I feel is exactly what a shounen series should be going for in order to appeal to its intended, younger audience. At the same time, older readers such as myself can acknowledge the effect that the story’s going for and appreciate the thought that went into such a development.
The end result should be that Naruto masters his Jinchuuriki chakra-infused Rasengan and uses it to turn the tides in the war — likely against Madara himself. For now, it looks like he’s going to be sidelined in training mode for some time, while every other ninja in the world puts their life on the line protecting him and Bee. I mentioned some time ago that I rather enjoy the training arcs in this series, since they show that there’s a methodology and concept behind all these techniques, so I’d be completely okay with that being the case. After all, they give us something to look forward to in the future when the new technique is finally put into use in a battle. This is in contrast to techniques that are whipped out of nowhere with a lengthy explanation attached in the middle of a fight, which is good for the surprise element but often leaves me wondering if the author came up with the idea just the week prior. There are definitely pros and cons to both approaches, so it’s always nice to see a balance of both in a series. In terms of a Dragon Ball Z reference, one of my favorite training arcs from that series was when Goku and Gohan were in the Seishin to Toki no Heya (a.k.a. Hyperbolic Time Chamber) and trying to grow accustomed to staying in Super Saiyajin form. There was a little bit of theory behind the process of doing so, and some of these Naruto training arcs are reminiscent of that.
As an indirect benefit, the inclusion of this most recent training arc does provide a means for Naruto to show up regularly in the story without having to join the war prematurely. As such, I can picture things jumping back and forth between the war and the time Naruto’s spending with Bee, possibly after each of the units have a run-in with Kabuto’s resurrected ninjas (much like this chapter). On that note, I like how this first one involving Kankurou’s unit included a more meaningful conclusion for Sasori. Even in death, he managed to turn a new leaf and save his own soul from being used as a tool. Along with the sentimental aspect, what’s worth noting about that turn of events is that it might be precursor of things to come. Namely, I can see the deceased ninjas’ lifelong goals/regrets becoming the key to releasing them from Kabuto’s control. We’ve already seen two such encounters from Shin and Sasori respectively, but there are still many more to come. Whatever the case, I’ll be looking forward to Shikamaru and Asuma should they meet. I’d say that encounter is all but guaranteed.