|Other Name(s)||Seal Eye|
The Fūingan is a VERY rare kekkei genkai because it is unlocked only for an extremely select few like the Mangekyō Sharingan or Eternal Mangekyō Sharingan. This dōjutsu was unlocked by the founder of the Uzumaki who was considered to be a grand master of Fūinjutsu due to his exceptional skill in in it which is in theory what unlocks this dōjutsu.
It was found that to actually unlock the Fūingan, the user must have the special chakra some of the Uzumaki have as well as Sage level chakra control and a mastery of over at least ten sealing techniques then they must channel ALL their chakra into their eyes while doing a hand seal for a Fūinjutsu. The result will be the user's eyes permanently change to that of the dōjutsu's. Unfortunately, this leaves the user without any chakra whatsoever and unable to regenerate chakra fully for two days as the chakra is used to properly accustom the body to the new dōjutsu.
This dōjutsu can also be unlocked during combat by using a sealing technique while the user strains their eyes though no one is sure how or why it decides to unlock during this time however, the user is still drained of their chakra though the technique can be completed and leaves the wielder of the dōjutsu without chakra for three days.
When the founder first attained this new power, he believed it to be a variation of the Sharingan or Byakugan however, he found that to be wrong, instead discovering the ability to weave seals with the eye to create dōjutsu techniques which can also be preformed with normal hand seals. The founder could also peer into a person's mind and look for mental blocks within the person's mind if he has eye contact but he can also create mental blocks and destroy them as well as strengthen or simply weaken the blocks of a person with eye dōjutsu techniques.
Unfortunately, the user is unable to read the person's mind like the hidens of the Yamanaka Clan but the seals the Fūingan owner can do are virtually limitless. In total, this dōjutsu has been unlocked four times in history however, all records of this secret dōjutsu was lost when the Uzumaki clan was scattered to the wind after their village was destroyed. however, the last one to unlock it placed a scroll containing it's information and hid it somewhere.