It is called a Torx screw. They are usually labelled T5 for a size 5 Torx, or TR10 for a size 10 Torx with a indent in the middle for special security screws. It is found in many consumer products, especially laptops, where they do not want you to remove components or casings. From the looks of it, it is probably between a size T5 and a T3. I have since sold my Japanese PSP due to financial issues, so I can no longer tell you the exact size. But iFixIt does sell a kit with the available sizes found here: Mako Driver Kit - 64 Precision Bits