The Kurogan is a dojutsu kekkei genkai unique to the Inazuma Clan. It is characterized by a black scelera and a yellow four-edged star in the middle.
The Kurogan only appears in a handful of the members of the Inazuma Clan, however, it is given from birth, rather than activated later. The reason behind this is thought to be that only those core fits into the Inazuma clan lineage is given the Kurogan.
When activated, the Kurogan gives the user chakra vision, as well as increased preceptive abilities. The extent of this may vary between users, depending on how well-versed they are at using the Kurogan. Along with this, it grants the user the ability to highten the sharpness of the eysight, such as being able to see the details of a tree from the other side of a field, at will. However, using this sharpened vision for extent periods of time causes ones vision to blur on a later occasion, usually when the Kurogan is deactivated. It should however be noted that this drawback isn't permanent, as with the Mangekyo Sharingan and ones sight usually returns to normal after an hour or two.
Though the users are born with differently powerfull Kurogan, a user might train it to become stronger. Different Kurogan has different potential. For example, a user can train his Kurogan to recognize or strengthen a special area of combat. A good example of this is Takis Kurogan, that has been trained to cast and recognize genjutsu. The most usual training imrovement however, is to train the chakra vision to the point that the user can see the chakra points. This improves ones ability to use the Stun Fist, a unique Taijutsu style used by the most skilled members of the Inazuma clan.