Ketsuryūgan

The Ketsuryūgan is a dōjutsu    kekkei genkai , which appears in certain individuals of the Chinoike clan. The Ketsuryūgan is recognised by its reddish colour, giving a special appearance for the users of this dōjutsu, characterised as holders of "eyes as red as blood". The Ketsuryūgan confers genjutsu casting abilities. Its power earned it comparison to the Three Great Dōjutsu.

The Ketsuryūgan also gave the users the ability to manipulate the user's blood, or more accurately the iron in the blood, allowing the user to not only manipulate their blood, but any liquid with high iron concentration (meaning that it may be related to the Magnet Release).

Trivia

 * When written as 血流, ketsuryū means "blood flow".