The Hunter's Eye (狩人の眼 Karyūdo no Me) is an ability possessed by Naoto Kurogane in his right eye, it allows him to see the numerical value of a person's life-force. Hunter's Eye is closer to an ability than it is a Drive. The Eye also determines who is the heir or leader of the Terumi Clan, leading it to be Saya Terumi's sole desire.
A person's life-force value dictates how much life they have residing within them. This value will decrease if a person is: sad, in pain, in despair or bitter; on the flip side, the value will increase if a person is: happy, feeling lucky, in love, embarrassed, impatient or even angry. Tadayuki Isa has a life-force value that is smaller than patients who have been hospitalized, something that Naoto notes to be strange.
As well as the ability to see someone's life force, it also allows the user to see what happens to a person when their life-force falls into 0. The result is the ability to see a form of noise consume and run havoc across the person's body until it forms into a black mass that resembles Arakune.
The following are the life-values that the Hunter's Eye reveals through the course of the Bloodedge Experience series.
- Naoto Kurogane — 9,810 – 0
- Haruka Hayami — 10,500 – 10,512
- Raquel Alucard — 80,000,000
- Tadayuki Isa — 925 – 1,007 – 217
- Rachel Alucard — None
- Valkenhayn R. Hellsing — 239,4211
- Relius Clover — 9,152
- Clavis Alucard — Too high to be measured
- Kana Kirishima — 9,006
- Saya Terumi — 7,946 – constantly changes because of her Drive and frail body