I claim the ornamental design for a portable personal storage device, as shown.
FIG. 1 is a top, left, front perspective view showing a portable personal storage device according to an illustrated embodiment of the invention;
FIG. 2 is a top plan view showing the portable personal storage device of FIG. 1;
FIG. 3 is a front elevational view showing the portable personal storage device of FIG. 1;
FIG. 4 is a right side elevational view showing the portable personal storage device of FIG. 1;
FIG. 5 is a left side elevational view showing the portable personal storage device of FIG. 1; and,
FIG. 6 is a bottom plan view showing the portable personal storage device of FIG. 1.
The broken line showings of the USB connector, key ring, and slide lever in the figures are for the purpose of illustrating portions of the portable personal storage device and form no part of the claimed design.