The effect is in the new "Picture Book Hall of melody"
If you use the glasses effect on the library a new book should appear in the southern shelves. Then afterwards you need to pick up a sparkling object on the west side of the room then exit out to the library again. A new npc should be running around the library which you have to catch. Then when both these tasks have been completed youll be able to enter the closed off area behind the desk up north.
Theres some eyeball npcs blocking the ladder, but if you enter the bar to the left and listen to the fellow in the corner, the npcs dissapear.
Then you just interect with the pink blob and you get the effect.