This article, Torii Seal, contains content taken directly from our mother site. All credit of such content is reserved the original authors over at Narutopedia, the original article can be read here: "Torii Seal".
When Naruto first obtained Nine-Tails Chakra Mode, his previous seal's outward appearance had changed into a shape of a magatama, along with a swirl design that resembled Uzushiogakure's symbol.
By using the seal's key, he can create several massive interlocking torii that can even immobilise and imprison Kurama with ease. Naruto then isolated Kurama's chakra in another part of him away from the fox itself in between four torii, so he could access it freely. It was later revealed that Kurama isn't always bound by the torii and has freedom of movement behind its cage, but Naruto can enter the cage without breaking the seal and still manipulate the torii to immobilise the fox if he wants.