This set includes the following DLC:
- Trails of Cold Steel BGM Selections
- Trails of Cold Steel II BGM Selections
- Trails of Cold Steel III BGM Selections
- Trails of Cold Steel IV BGM Selections
- Trails from Zero & Trails to Azure BGM Selections
- Arranged BGM Selections
- Vocal Music Selections

More details on the official game page of Trails through Daybreak II - BGM Pack ...