Sensor

A is a type of ninja that is capable of detecting the presence of other people through their chakra.

Overview
A skilled sensor can detect their targets from a great distance, as well as differentiate the characters by their chakra signature alone. They are even able to tell when other sensors are using their abilities.[3][4] Karin is able to tell exactly who is among a crowd of people and her sensory skills are such that she is even able to tell if her targets are lying based on any fluctuation of their chakra. Mū can discern between chakra signatures of shinobi from different populations. There are, however, methods that can hinder a sensors ability to detect individuals. Mū has mastered the Hiding with Camouflage Technique to such extent that he is able avoid detection by traditional sensory techniques, but can be sensed through other means such as contact type sensory techniques. Karin is able to suppress her chakra though she herself cannot use her abilities while doing this. The Aburame can use their insects to create false chakra signals and confuse sensors. The Mirage Genjutsu used by the Second Mizukage and his Giant Clam also prevents them from being sensed through traditional methods while in effect. Zetsu is also able — through unknown means — to render himself undetectable.

Throughout the series, various characters have commented on the 'feel' of a person's chakra and similar comments regarding the ability to sense high levels of chakra a little, leading to the possibility that chakra sensing is merely a more refined version of this by either teaching or being simply born more sensitive. Several other methods of sensing have also been displayed such as Gaara's Sand Sensing technique which is a contact type (接触タイプ, sesshoku taipu) sensory ability as well as Nagato's Rain Tiger at Will Technique.

According to Karin, sensor types have different specialties depending on their villages: Konoha shinobi often use ninken with their smell and tracking sense. Karin's sensing abilities are derived from her Mind's Eye of the Kagura; it is unknown if other sensors also have a specific techniques to do so, or if it is just a general skill.