The Storefront was first introduced in the imaginary universe when it distracted
Problem Sleuth with a Window filled with light and music, later revealed to be a portal into the Hysterical Dame's Music box. The window's light soon went out, causing a monster to appear in front of Problem Sleuth, getting him killed.
Later, Ace Dick used the Storefront Portal to avoid falling to his death, which consequentially shrank him due to the size-warping capabilities of window portals.
The Music Box half was then sliced in half by the Hysterical Dame, never to be used again.