Taking a life has a more profound effect on your psyche than most would think. That's why you feel that way.

[To him, there's no worse punishment than the weight of a life on one's shoulders. That's only if the killer has a conscience, though, and he wants to hope that this admission of confusion means Kaoruko has it, even if he's only known her for a week.]

Regardless of what happens next, that's going to stay with you for the rest of your life.