I believe it's called 'murderer', 'killer', or even 'manslayer' if one must. 😛 I get keeping it for the Japan-styled protagonist, to a certain extent, but for the pseudo-german guy?
Have you considered using 'favorite'? Doesn't help with verb usage, though.
Edit: Oh, it was already suggested three posts before mine, by beep_repair. Guess that's what I get for skimming over the last bits.