Senjutsu

refers to the user's chakra created from spiritual and physical energy within the shinobi as well as energy from nature. This drastically increases the strength of all physical attacks and jutsu. It would seem that it stems from the toads, as only Jiraiya, Shima, Fukasaku and Naruto have been shown using them, and Gamakichi being the only one who is familiar with it.

Requirements for using Senjutsu
Only those who possess a high chakra level can invoke Senjutsu. The user is required to balance his physical and spiritual energy with the natural energy he gathers from Nature. If the user puts too little natural energy into using sage techniques, the technique will not initiate and if the user puts too much natural energy into the techniques, the user will start to turn into a frog. Further more, while gathering Natural Energy the gatherer must remain absolutely still in order to be one with Nature.

Method of Reversing Toad Transformation
Getting hit by a special scepter 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 since there is no other known way to reverse the toad transformation. Furthermore if the Transformation is completed then not even the staff can reverse it.

Further Information
Jiraiya, a legendary Sannin, had trouble using his sage form and he slightly turns into a frog. This involved his nose and hands and face changing to a more toad-like appearance. However, Naruto, who has just learned how to sense natural energy and create sage chakra, only has dark rings around his eyes and horizontal, slit-pupils showing his mastery over his Sage form. He is still able to use his sage chakra well, since he was able to lift a giant frog statue with his sage chakra, but accidentally drops it prompting Fukasaku to remark that even though Naruto is learning at a faster pace than Jiraiya, he's still very clumsy.

Before Naruto was able to utilize the sage chakra correctly and evenly, he used frog oil, which allowed the natural energy to enter his body.

Techniques

 * Hermit Mode
 * Hermit's Art: Hair Needle Barrage
 * Hermit's Art: Goemon
 * Hermit's Art: Great Ball Rasengan
 * Demonic Illusion: Toad Confrontation Singing
 * Super Great Ball Rasengan
 * War of Words Decapitation
 * War of Words Binding