"Unprecedented Shivers" (かつてない戦慄, Katsutenai Senritsu) is chapter 412 of the original Naruto manga.
At Mount Myōboku, Naruto asks to train with shadow clones to help his learn senjutsu faster. Fukasaku agrees, but they do not help much. Seeing that Naruto is having trouble, Fukasaku informs him that not everyone can learn senjutsu; only those with large chakra reserves and the determination to never give up can do so. Naruto is happy to find he has plenty of both. Meanwhile, Karin heals Sasuke's injuries while the rest of Taka fights with Killer B. Seeing that they might actually be a challenge, B decides to go all out.