The ornamental design for a displaycase, as shown and described.
FIG. 1 is a first perspective view of the display case.
FIG. 2 is a second perspective view of the display case.
FIG. 3 is a top view of the display case.
FIG. 4 is a bottom view of the display case.
FIG. 5 is a front view of the display case.
FIG. 6 is a rear view of the display case.
FIG. 7 is a right side view of the display case; and,
FIG. 8 is a left side view of the display case.
The broken lines showing of a transparent top panel, a transparent left side panel and a transparent right side panel as well as features on the bottom and rear are included for the purpose of illustrating environment and form no part of the claimed design.