Silver eyes begin as the (non-silver) eyeballs of a special breed of hyena from Lospass Island. When placed in the eye socket of a human being (consistently shown to be the left socket), they have the potential to silverize, which grants the human supernatural powers, most prominently immortality and youth. The full extent of the powers and mechanisms of the silver eye is unclear; it is stated in Flower, Sun, and Rain that two silver eyes in the same place invokes the "will of God" which warps time, for example.
Silver eyes were originally utilized in ancient Sundance Tribe rituals. In the events of the Silver Case, Japanese politician Uminosuke Hachisuka acquired a silver eye from a Sundance man, Format Kamui. The Shelter Kids Policy was put into place partially as an attempt to manufacture more; however, it never succeeded, and all hyena eyes in the program failed to silverize.
List of known silver eyes
- Format Kamui had a silver eye inserted into him at the age of two. This eye was later stolen by Uminosuke Hachisuka, and even later stolen from him by Tokio Morishima. This eye was seemingly taken from him before the events of The 25th Ward: The Silver Case.
- Tetsugoro Kusabi had one as Peter Bockwinkle. It's unclear if he kept it afterwards, or if the eye was ever put into Kusabi's actual person; it is possible it was only a part of the Bockwinkle disguise.
- The bomb-fitted clone of Step Sding seen in Flower, Sun, and Rain had one before he exploded.
- According to Famitsu interviews, Catherine has a silver eye in its core, though Sumio Mondo is not aware of it.
- Yotaro Osato appears to have two silver eyes.
- Sundance Shot has been strongly suggested to have had a silver eye at some point, though now he wears an eyepatch.
It's entirely possible that some of these silver eyes are one and the same, having moved hands at some point, especially seeing as Sundance may have had one that is no longer there, and the various instances of plugging into eyes that Catherine performs.