Torii Seal

When the Nine-Tailed Demon Fox's Yang chakra merged with Naruto, his previous seal's outward appearance had changed into a shape of one of the Sage of the Six Paths' magatama beads, along with a swirl design that resembled the symbol of Uzushiogakure, appearing on his Nine-Tails Chakra Mode shroud. By using the seal's key, he can create several massive interlocking torii that can even immoblise and imprison the Nine-Tails with ease. Naruto then isolated the Nine-Tails' chakra in another part of him away from the beast itself in between four torii, so he could access it freely. It was later revealed that the Nine-Tails 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 beast if he wants.

Influences
A is a traditional Japanese gate most commonly found at Buddhist temples and Shintō shrines, where it symbolically marks the entrance to a sacred area. Torii were traditionally made from wood or stone, but today they can be also made of reinforced concrete, copper, stainless steel, or other materials. They are usually either unpainted or painted vermilion with a black upper lintel.

Located in Kyoto, Fushimi Inari-taisha, which is the head shrine of the Shintō kami Inari, is very well known to hold thousands of such torii.

Trivia

 * When this seal was made, the Nine-Tails made an allusion to the Sage of the Six Paths in regards to the seal, but the beast never finished its statement.