I Do not own Naruto, Bleach, Inuyasha, or Yu Yu Hakasho though I would like to!.
The Rise of the Kurogan
Prologue: History of the Kurogan
The Dark Fox eye, better known as the Kurogan, named by those who feared the twenty Kitsune no Kyubi that reigned over the ten breeds of kitsune youkai allows those with the ability to become a kitsune, see 360 degrees, see through any genjutsu and object, copy and predict any movement, genjutsu, ninjutsu, taijutsu, and kenjutsu, and control any type of element and chakra once the wielder obtains his/her's ninth tail.
Also, they grow angel wings that reflect the purity and hardships of their soul, ranging from pure white, which signifies a pure heart, to jet black, which signifies a treacherous, evil heart, but few are known to have silver wings which show that despite the fact they had many hardships and trials as a child, that would have made most become psychopaths, crazy and senile, or mass murderers, instead still have a heart of pure gold and diamonds. Their wings can be any color that corresponds with the ten kitsune breeds and each wielder has the chance to become either the male or female Kitsune no Kyubi of that particular breed for once the Kurogan is activated it's wielder becomes a pure blood fox demon, or youko despite the fact they have wings.
This is because their wings are of another kekkai genkai which is called the Tenshigan, or angel eye, that makes the wielder an angel of an element. Also, they can make it where their wings only appear when needed instead of being out all the time so they can lead the normal life of a youko. Many youkai call them celestial youko since there is a "Kurogan" for every basic type of demon, making it where the "Kurogan" wielders can save a dying breed of youkai depending on their fur color or elemental ability depending on both breed and type.
The Kurogan branches from two different kekkai genkais that were both gifts to two different families that had their son and daughter become a mated pair, or a couple in human eyes, and instead of their kekkai genkais destroying each other they fused and made an entirely new doujutsu, as eye kekkai genkais are called. Two doujutsus are branched from the Kurogan and they are well known since they are the Uchiha's Sharingan and the Hyuga's Byakugan though neither would admit that their eyes are from the supposed, "Evil eyes" since they both have large, almost godlike egos unlike their original family, the Uzumaki clan that was thought to be wiped out when Whirlpool country was destroyed, ending the Kurogan's powerful abilities and the possibility to remake the Sharingan and Byakugan if either were to be wiped out.
Despite the fact many think the "Kurogans" are evil they really a gift to the two mates, whose families had forced to become mates before being outcast since they didn't have their families original doujutsu, from the three gods; Yami-sama, Kami-sama, and Shimigami-sama since both loved their families very much and had been forced to abandon their loved ones who had always looked down upon them despite the fact they tried to always help them.