Hi guys !
For this achievement you have to feed the Cat NPC with a specific fish.
This fish can only be found in the pond,in the nightmare.
You can see me doing this in my full achievements video guide from 0:07:59 to 0:11:50:
If you prefer a text guide:
Collect vials from the church guy.
Go to the lake,grab the knife at the tree at the left of the entrance.
Cut the rope attached to the boat on the island.
Grab the fishing rod from the boat.
Go in the house and use the bed to go in the nightmare (pink sky with kanjis everywhere)
Go to the pond,use the fishing rod and grab a fish here.
Go back to the normal world and feed the Cat with the fish.
*Achievement unlocked*
Have fun !