Sage Mode (Ishi)

is the result of using along with a shinobi's — or in this case Ishihara's — own.

Overview
Sage Mode is the empowered state humans enter when they learn to draw natural energy inside them and blending it with their chakra. By doing so, the human creates new senjutsu chakra that allows them to enter Sage Mode. Sage Mode enhances the combat efficiency of the user by allowing them to tap into the natural force of the world that opens new techniques to the user and allows them to power up existing ones with the new senjutsu chakra.

Thus far, Sage Mode has been shown to be taught in two places: at Mount Myōboku by the, and Ryūchi Cave by the. Learning Sage Mode at Mount Myōboku or Ryūchi Cave grants the user with a toad and snake-influenced Sage Mode respectively, which carries over the same advantages and disadvantages, only differing in application.

Training
According to Fukasaku, only those who already possess "extreme chakra levels" can utilise natural energy to invoke senjutsu. Also, the user's body must be strong enough to support Sage Mode; Orochimaru learned senjutsu but was unable to use Sage Mode because his host bodies were not strong enough to support this power. Stemming from this and his experiments with Jūgo's unique ability, however, he was able to create his own brand of unique.

The user is required to balance his/her physical and spiritual energy with the natural energy he/she gathers from nature; compares the process to adding an extra flavour to a chocolate and vanilla swirl ice cream. If the user puts too little natural energy into using senjutsu, the technique will not work.

In order to enter Sage Mode, the gatherer must remain absolutely still in order to be one with nature and balance the natural energy with their own physical and spiritual energies. Those learning from the toads have access to a special toad oil that allows the natural energy to enter their body, but this oil only exists in liquid form in Mount Myōboku's atmosphere. The oil evaporates if it is taken outside, thus rendering it useful only for learning purposes. If the user takes in too much natural energy, the user will start to turn into a toad and, eventually, turn to stone. The petrified remains of one-time apprentice Sages who failed to master senjutsu are spread throughout Mount Myōboku.

Getting hit by a special staff during the transformation will reverse the toad transformation by knocking all the natural energy out of the gatherer. It is dangerous to learn how to gather natural energy without the staff because there is no other known way to reverse the toad transformation. Furthermore, if the transformation is completed, not even the staff can reverse it, and the user would become a toad statue forever.