the achievement trigger at first press start after install dlc you can try this： delete savedata and start the game again (after backup your savedata) location of savedata: C:\Users\{your username}\AppData\LocalLow\DSGame\Seek Girl V (Delete the file named 

Since it's been asked a few times in the discussion and all anyone ever says is let the cut scene finish without any explanation, I bring you... Fire this guide on how to get the bloody achievement.