The trophy list for Lone Survivor lists a Yellow ending, it's one of the new, hidden endings in the Director's Cut edition. How do I get the Yellow ending? I haven't noticed any new items since beating the game with the 3 "normal" endings.
First get the White Ending, getting the White Ending while unlocking the Yellow ending will save you a full playthrough.
All you need to do is play a new game plus (beat the game and then play again) and attempt to give your Sleepy Cat doll to every human character in the game (possibly plus your Cat). Since doing this also gives you the ingredients for the Ultimate Burger, a key part of the White ending, it's important to do these in tandem.
The characters to give Sleepy Cat to are as listed. Most interactions are missable so check the conditions:
After you've done this successfully, finish your playthrough and start over. If it worked, you'll see a pictures of You cuddling with Sleepy Cat during the intro. Then go back to Chie's apartment and give her the cat. Your game will immediately end with a new scene and you'll get the new ending. It takes about 10 minutes to get this after unlocking the Sleepy Cat intro scene.