This simple, no solder, mod will let you play Japanese titles on your US N64 or vice versa. Simply disassemble your N64 and replace the existing cartridge slot bracket with this universal bracket. It's that simple.
Note: PAL and other region N64 consoles have a special lock out chip that won't allow you to play on NTSC consoles and vice versa. This bracket will not make those consoles region free, sadly.