Prologue is the first section of the Clair Obscur: Expedition 33 story. This section has 2 collectibles and 1 missable trophy related to one of the collectibles. The second collectible is HIGHLY MISSABLE and if it is missed prevents you from obtaining a Journal later in the game, requiring you to do a full second playthrough as the Collectibles don’t carry over into New Game+.
All collectibles are listed in the general order they can be obtained throughout the story. By following this you will get everything needed for trophies & achievements. There are many other items to pick up such as upgrade Materials for Expedition resources, Pictos, and Outfits, but these aren’t required for any trophies and aren’t listed in this walkthrough.
Collectibles Overview:
Prologue
Main Street
Record #1: Lumiere – While exploring the Main Street with Sophie, continue to the far end but don’t go down to the dock (there is a confirm dialogue before you do this which progresses to the next area). On the right side near the stage with dancers is a robotic Mime. Interact with it to start a battle after which you receive the record. You can retry this fight as many times as you want if you get knocked out. Note this Record can be obtained later if you didn’t obtain it here, but the trophy/achievement 
A Peculiar Encounter is for specifically beating this Mime, which you can do on a new save or in New Game+ if you missed it here.
Festival
MISSABLE KEY ITEM: Old Key – Once you reach the festival area you automatically receive a Festival Token. These are used to trade for three items in this area. Immediately walk to the woman at the back left in the third stall. Agree to trade her the token to receive the item Old Key. This key is required to open a door and receive a Journal later in the game. If you don’t obtain this key before exiting the Prologue you cannot obtain that journal, and thus cannot earn the trophy/achievement for obtaining all journals in this playthrough, and would need to collect them all again in a second playthrough. If you trade this token for something else first you can obtain two other tokens by interacting with the man in white or beating Maelle in a fight before leaving the area.
Next up: Act 1
SerahsArmpits says
Not trophy related, but on the left side before some people blocking your way is a trash can. If you examine it 4 times, it gives you a Chroma Catalyst and the same spot near the end of the story will give you a Perfect Chroma Catalyst. These are limited until NG+ and are otherwise very difficult to get!
Matt1yu says
Appreciate the tip, thank you!
Chris says
Can you be more specific? There are seven trash cans. Is it near the Harbor, or?
sci says
It’s near the painter, across from the girl playing the guitar