Premise: The character is not specifically investigating Kira, but they fit the description for Kira's MO, whether that's a criminal, a billionaire, or what have you. And they are aware of this fact.
Their true name, by whatever explanation you fancy, is not already public. Can they keep it that way?
Survived - They outlive Kira
Survived - Kira gives up
Dead - Hard-fought battle
Dead - Decent struggle
Dead - Slight inconvenience
Dead - Another name on the list














