To redeem DLC items in Monster Hunter Stories 2, you must first head into a nearby village and locate an NPC called Connecticat, and talk to them. Once you talk to this NPC cat, you will be able to redeem any and all DLC items you currently own by clicking the button that says downloadable content.
After this, you will be presented with a list of DLC, and you will need to click on all of the ones you own to redeem them. When you finish, these items will then show up in your game once you reach the second portion of the game or go to the change appearance option in the game.
That said, if the items you claimed were for Ena, you will need to go back to your house, open the chest inside, and then hit the option that says Navirou's Outfits to use them. As for any character customization and layered armor items you may have claimed, you will need to open up the character customization menu to use these items.
Layered armor can be accessed via the last button on the left of your screen, while other items such as makeup and hair can be accessed with their respective buttons.
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