The Shadow Imitation Technique allows the user to extend their shadow on any surface (even water) and as far as they want as long as there is a sufficient area.
Once it comes into contact with a target's shadow, the two merge and the target is forced to imitate the user's movements. Therefore, the two can throw shuriken at each other at the same time if the user desires that (of course, to prevent hurting themselves, the user just has to have the shuriken holster in a place where you don't normally have it, like the back, so that the opponent draws nothing when the user draws a shuriken). If the target is out of range, the user can produce a better light source to increase their shadow's size or rely on pre-existing shadows for their shadow to freely travel through. It's also possible to split one's shadow, either to trap more opponents at once, or to create a distraction. The shadow can also be attached to people without binding them, letting the "victim" move freely. Doing that has the purpose that the person, the shadow was attached to, makes contact with a third person, to bind the latter one with the shadow.
The major downside of the Shadow Imitation is that it is tiring to use repeatedly; Hidan notes that the ability is subject to some form of diminishing return and decreases in potency after repeated use (Shikamaru can only maintain it for 5 minutes per use). If the user is low on chakra, the performance rate of the technique also deteriorates. Insufficient lighting will make the technique less effective. A particularly strong opponent can also resist the shadow's forced imitation.
It was originally created somewhere in Konoha's region as a way to capture deer for their antlers. From there, it was treated as a secret technique, and transmitted to the following generations.
Shikaku Nara calls this technique by its old name: the Shadow Bind Technique (影縛りの術, Kageshibari no Jutsu; English TV "Shadow Paralysis Jutsu") (exactly "Leaf Secret: Shadow Bind Technique" (木ノ葉秘伝・影縛りの術, Konoha Hiden: Kageshibari no Jutsu; Literally meaning "Tree Leaf Secret: Shadow Bind Technique"). Shikamaru also uses this name in Naruto Shippūden 2: Bonds. The old version simply paralysed the target. The imitation aspect was apparently added sometime between Orochimaru's defection from Konoha and his later invasion of the village.
Ensui initially referred to this technique as the Shadow Imitation Shadow Bind (影真似影縛り, Kagemane Kage Shibari) but later refers to it simply as "Kagemane".
It does not appear to affect the opponent's face, allowing them freedom of speech, thus this technique can be used for interrogation purposes.