Yamigan (Literally; Darkness Eye) is a powerful doujutsu exclusive to the Cipher Clan.
The Yamigan is known to have a wide variety of abilities. Their are three abilities known currently. The first of these known abilities is the ability to see chakra. The user of this eye power has the ability to see chakra flow and such. Like the Sharingan, the Yamigan gives everyone a different chakra color to differ them from others. The second ability of the Yamigan is the ability to copy techniques. The Yamigan can copy almost all techniques, that excluding Kekkei genkai and Kekkei Tota. And it can copy simple things such as pencil movements and handwriting. The third ability of the Yamigan is that it boosts the user's strengh incredibly. And if the user pushes themselves to their absolute limit, the Yamigan will change into the Mangekyo Yamigan, which boosts their power even more.