it has been explained./...more nartu wiki... Perfect Sage Mode
Minato's Sage Mode, learned by the toads.
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Unlike Jiraiya, Naruto Uzumaki, Minato Namikaze, Kabuto Yakushi and Hashirama Senju were able to perfectly balance the natural energy with their own chakra. This allows them to use Sage Mode in perfect balance, which allows them to retain all of their previous physical characteristics. However, those who master Sage Mode have a distinctive marker, which is a dark pigmentation around their eyes. While the actual design of the pigmentation and the user's eyes usually differs from Sage to Sage, Naruto Uzumaki and his father, Minato Namikaze, appear to bear identical such designs.
Naruto and Minato had orange pigmentations around his eyes and with a yellow toad-like iris. Kabuto Yakushi had purple pigmentations around his eyes through to his shoulder blades and with a yellow snake-like iris. His snake-like characteristics progressed further in Sage Mode with him growing four horns, with him stating metaphorically that he'd transcended from "snake" to "dragon". Hashirama had red (black in the anime) pigmentations around his eyes through to his ears and with a yellow iris. He also had a red pigment (black in the anime) on his forehead that resembles an eye. His eyes were different from the Toad and Snake Sage Mode as his did not bear any animal traits.
A true sage would still suffer from the weaknesses of Sage Mode, requiring that they use Sage Art: Amphibian Technique in a battle situation so that they could stay mobile. However, Kabuto Yakushi assimilated the DNA of Jūgo to replicate his clan's ability to passively absorb natural energy, thus allowing him to continuously collect the energy even while moving, bypassing this particular weakness.
As his own workaround, Naruto has some of his shadow clones gather natural energy elsewhere while he fights. Once he has run out of his own senjutsu chakra, he reverse summons the clone and has them disperse, giving him the clone's natural energy and allowing him to enter Sage Mode again. This method limits the maximum number of shadow clones that Naruto can create to five for as long as the clones are gathering natural energy, as anything more would interfere with their focus. To make sure he has enough shadow clones for use in battle, Naruto has only two shadow clones gather senjutsu chakra, allowing him to enter Sage Mode a total of three times. Naruto has also stated that it is possible to lengthen the time he is in Sage Mode.[8] Naruto, Hashirama and Minato's skill in senjutsu is such that they can enter it in moments.[9][10][11][12][13][14] In addition, Naruto's old limit of two Rasenshuriken has been increased to three,[15] five in the anime.[16]
