Senjutsu (仙術, lit. "Mystic Arts", "Sage Techniques", Xi'an Shen) is the name of a Chinese martial art of mythical and legendary proportions. It is said to have been used by the immortal mountain hermits of Taoist myth, and is centered on the exercise and mastery of one's ki.
One such character, Oro, is a master of Senjutsu (called a Sennin) that appears as a playable character in the series. He is to date the only known user of this martial art as many of his apprentices and pupils are unable to endure the exceptionally harsh training to master it.
Despite linguistic usage, Senjutsu is merely a Japanese umbrella term used to refer to the arts said to guide and refine one into becoming a Xian, the legendary fairy and genie like beings of Asian myth who are immortal and bear great supernatural power. Though its lore and mythology are up to debate on whether such ways truly do allow people to become Xian, Senjutsu's origins tie in deeply with the Chinese arts of Taoism and Tai Chi Chuan, including the ki centered arts of Neidan (internal alchemy), Qigong, and Daoyin, from the archetype of the so called "Xian", or enlightened being, being described in the writings of Chuang Tzu and the Huangdi Nei Jing Su Wen and to even the arts from ancient shamans of pre-united China. The mastery of such school's ways of living were said to allow one to carefully balance their being to allow them the secret to immortality.
In the subject of martial arts, the mythical ascended Xian and Taoist priest Zhang Sanfeng is said to be the legendary founder of the aspects of Neijia, or internal focused martial arts, those of which focused greater on the mental conditioning of being in tune with one's body and drawing upon the aspects of ki.
Depiction in Street Fighter
Esoteric and majorly unknown in its regards to its practices, the art is hinted to revolve around drawing upon the latent power within oneself, and learning how to communicate with heaven and earth. Training and study of Senjutsu is described to be extremely rigorous, demanding, and a vast investment of time, desiring only those who are utmost willing to learn its secrets in the years needed to master it.
Mastery of these legendary practices were said to grant the practitioner fantastical powers; such powers include superhuman strength, prowess and agility, as well as longevity and/or effectively immortality. A Sennin can manifest their ki into corporeal form with ease and use it to perform telekinesis; they can also survive and withstand environmental and atmospheric conditions too extreme for a normal human being.