Name: Kiri no Kabe
Type:: Ninjutsu
Rank: C-S

Abilities Gained: This ability is one that focuses on an alteration made to the body by a shinobi named Gen, who thought he had found the keys to immortality. He altered the body now referred to as Kurai so he could use it as his own, he tank bred bodies for many years trying to find the mix of abilities he wanted for himself. This was the last subject before he was slain. The alterations to this body and intentional breeding caused it to have a few unique traits, these traits are as follows:

• Blood Overproduction – This body was bred with a trait that causes too much blood to be produced, meaning that excess blood soaks into the body and tends to seep from the person's eyes, and the person tends to cough up blood quite often.
  
• Marrow Alteration – The marrow in the body is altered to produce a special cell (dubbed IR-cell5527 by its maker) that is mixed throughout the body’s circulatory system.
  
• - IR Cells – IR stands for infection-reactor cells. These cells have three purposes, the first is that they replace white blood cells and do their job through an ‘infection’ process that kills or negates whatever foreign entities (germs, viruses or venom) it comes into contact with by absorbing them and allowing itself to die. The third purpose is to, upon dying, breakdown into a chemical that is highly reactive to the chakra of the body it is produced by.
  
• Blood Control - The high reactivity of the chemical that is in the blood to the bearer’s chakra allows the person to control and manipulate their blood with little effort.
  
• Excessive Skin Growth – Due to the predicted damage fighting with one’s own blood it was bred in for the body produce excess flesh to speed recovery and protect the body from accidentally reopening older wounds that are still healing.

Disadvantages: Opening too many wounds will cause enough blood loss to pass out then die if one isn’t careful. Also the more one uses the abilities granted by this bloodline means more and more of one’s white blood cells are dying, and less white blood cells means more likely to die from getting sick and longer recovery times.

Other Effects: Due to the effects of this ability the soaking in of blood to the skin causes a darker red skin tone and a deep red color to the nails of the body, and excess blood to the eyes causes the body’s eyes to always appear ridiculously bloodshot.


Rank Specifics

• Genin: Very minor control over blood; can influence small clotting and can use blood to make techniques slightly easier to perform or to make them barely stronger (not a rank higher, just for aesthetics at this level).
  
• Chunin: Improved control over blood; can intentionally clot moderate amounts of blood and can use one’s blood to bump the strength of techniques by one rank (up to a max of B-Rank) strength by using blood in the techniques themselves.
  
• Jounin: Impressive control over blood; can quickly clot large amounts of their blood intentionally, and can use their blood to bump their techniques strength or ease of use (C and lower bumped by two ranks and B bumped by one).
  
• S-Ranked: Master blood control; can near instantaneously clot large amounts of their blood, and can use their blood to bump their techniques strength or ease of use (B and lower bumped by two ranks and A bumped by one).
  

I do believe this would be better classed as a KKG/clan rather than a rare ability.