Here is the full list of all 39 Paradise Killer achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
Achieve max hangout level with Henry
Achieve max hangout level with Carmelina
Achieve max hangout level with One Last Kiss
Achieve max hangout level with Akiko
Achieve max hangout level with Sam
Speak to every Shinji
Find all recordings
Achieve max hangout level with Witness
Achieve max hangout level with Doom Jazz
Achieve max hangout level with Lydia
Achieve max hangout level with Crimson
Achieve max hangout level with Yuri
Access the barracks
Collect all drinks
Acquire Elusive Chocolate
Tell the ghost what happened to their friend
Complete the Syndicate HQ puzzle
Unload the cargo
Speak to a [REDACTED]
Visit [REDACTED]
Use the [REDACTED] to open the [REDACTED]
Acquire the Pyramid Starlight upgrade
Tell the ghost who they are
Unlock all footbath upgrades
Activate all Crying Grudge statues
Return the missing gem
Acquire the Cosmos Starlight upgrade
Give a treat to [REDACTED]
Deliver the manifesto letter
Acquire the Worship Starlight upgrade
Deliver reassurance that justice was done (it wasn’t)
Complete the valve puzzle
Access the Syndicate Graveyard
Collect every shrine tablet
Collect all Island Sequence Mementos
Find all music tracks
Speedrun the game and complete it in under 10 minutes
Collect all Starlight Skins
Collected all bottles of whisky