Kanetsugan

The Kanetsugan (The Eyes of Heat) is the Kekkei Genkai of the Ooinaru Clan and can be used for two purposes: A. being to see and detect body heat and B. being able to manipulate the fire chakra nature to another level. Most members of the Ooinaru Clan have black pupils, when the Kanetsugan is activated, orange markings will begin to appear on their pupil. There are three levels of the Kanetsugan, each level allowing the user to see body heat to a different degree.
 * Level One: The pupil will have a small orange circular marking in the middle. This level is more associated with Genin and the user can only see body heat in their immediate area.
 * Level Two: This level is more associated with Chunin, at this stage two orange circular like markings will appear on the pupil. At this level, the user can see body heat up to around a maximum of 200 meters.


 * Level Three:  This level is more associated with Jonin, at this tage there are two orange circular markings in the user's black pupil. There isn't a known maximum distance in which a user can see body heat at this level, it seems to vary with how much training a person has with using their Kanetsugan.