This character has heterochromia iridum (usually shortened to heterochromia). That is, their irises are different colours.
There are several types of heterochromia. In complete heterochromia, one iris is a different color from the other. In partial heterochromia or sectoral heterochromia, part of one iris is a different color from its remainder.
In visual novels, "heterochromia" usually refers to complete heterochromia. It may occur from natural causes, but is often indicative of a supernatural characteristic.
When using this trait, also include the traits for the individual eye colours.
For characters with central heterochromia, use Central Heterochromia instead of this trait.
Differently colored eyes