Senjutsu

is a specialised field of techniques that allows the user to sense and then gather natural energy. Senjutsu practitioners learn to draw the energy of nature inside of them, blending it with their own chakra. This adds a new dimension of power to the practitioner's chakra, resulting in the creation of. Senjutsu is uniquely invulnerable to Truth-Seeking Balls.

Those that can absorb or manipulate senjutsu chakra are known as. Generally, senjutsu chakra cannot be used by those untrained in senjutsu; those who are enter a form called Sage Mode, increasing their physical parameters for as long as the mode is active. Because of the steep prerequisites of Sage Mode and the risks involved just in learning how to use it, there are other methods:
 * Members of Jūgo's clan can passively absorb natural energy, mutating their bodies. But because they cannot control the chakra they are creating, they tend to go into berserk rages.
 * Orochimaru experimented on the enzyme responsible for these rages, and uses that as the basis of his cursed seals, which absorb the wielder's chakra and in return feed them Orochimaru's senjutsu chakra.

Trivia

 * In the anime, the sound of natural energy being gathered to form senjutsu chakra is the same as the one used for the healing green chakra of the Mystical Palm Technique.
 * The word uses the same hiragana (せんじゅつ) as the Japanese art of, possibly an allusion towards Sages' ability to sense while in Sage Mode.
 * In the ninth Naruto OVA, use of senjutsu during the Chūnin Exams is against the rules due to it giving Naruto Uzumaki an unfair advantage.