Paradise Killer - The Last Whiskey and the Last Three Starlight Skins

 I was able to find most of the achievements in Paradise Killer by using the Meditation skill and hunting down all the hearts. That doesn't work for the last whiskey, Evening Melancholy, and the last three starlight skins; Ancient Battlefield, Dimensional Breakdown, and Symbols of Day Break. To get those, you need to speak to the ghost of a fish on top of one of the danchi (blocks of flats). 

From the pier where Lydia hangs out, it's the building right in front of you. Climb to the roof and talk to the fish ghost.

The fish will ask you a few questions that Lady Love Dies will answer automatically, if you've found the thing he asks about. If you're at the end of the game and you've hunted down all the hearts, you should have those answers. They're associated with relics, from what I recall.

Once you've got all 55 Starlight Skins, you'll get the Generation Remix achievement. Once you've found all 12 whiskeys, you'll get the Conversations about the Future achievement.

When I spoke to the fish, I'd unlocked every achievement apart from the two listed above and the speed run, and I had no trouble answering any of the fishes questions.