Hensōjutsu (変装術) is a Japanese martial art skill involving disguise, impersonation, and infiltration.In some ninja clans it is known as the "Shichi Hō De" (七方出) or, "seven ways of going" (one form of ninjutsu that has a person play a role much like an actor does in impersonating people). This is an actual physical transformation that is typically used to change into people other than oneself, but one also has the ability to change into animals, plants, and even inanimate objects like weapons. This gives this technique an abundance of uses. The transformation of a skilful shinobi will be exactly like the genuine article, so it will be impossible to tell the two apart. On the other hand, a transformation performed by an inexperienced person will have obvious discrepancies. It will be impossible to deceive anyone with it. This technique requires a high amount of skill to perform as it requires constant emission of energy while mentally maintaining the form. On top of that, the user would be, most likely, interacting with the environment. This puts mental strain on an inexperienced ninja. Thus the best way to determine if it is indeed a transformation is to cause this strain upon the user; though this is of course not always successful.
Advanced versions of this technique allow the ninja to make the technique permanent so that they don’t need to exert themselves to maintain it for a long time. This is mainly used as a way to maintain ones youthful appearance and vitality