Throughout the story there are hidden beads which you can find. There are a total of 30 beads to find. They are found in presents hidden in rooms or in presents found after beating a guitar solo. The beads offer perks to a multitude of things and are quite useful. To equip one hit the button and sort through your inventory by using the . You’ll find a menu of all the beads you’ve found, press on a bead to equip it. Once you pick up a bead you’ll have it through all difficulties.
You'll find a complete list of the Ghost Beads in this thread.