A DLC exclusive attachment item set that lets characters place certain Pom Pom Pals (Pom-ified versions of characters) on top of their heads. Contains the following cosmetic items:

Joshua Pom Pom Pal x8
Olivier Pom Pom Pal x8
Kloe Pom Pom Pal x8
Tita Pom Pom Pal x8

※After purchase, items can be obtained in-game by selecting ITEM from the main menu, and then selecting newly added content within the DLC tab.
※After items are obtained, they can be equipped via the COSTUME section of the main menu.
※This content is part of the Trails in the Sky 1st Chapter Season Pass, but can also be purchased separately. Please be careful to avoid purchasing the same content twice.
※The main game Trails in the Sky 1st Chapter is necessary to use this content. In the event the latest patch is necessary, please update the game first and then make use of the content.

More details on the official game page of Pom Pom Pal Set B ...