The cable is a DIN 5-pol, but it is a very NEC customized cable. So unless you can't find a deticated cable (in hard off junk cable boxes etc.), you will be kinda lost. Sure you also may check the super potato in denden town, but they will charge you like extra 3000 yens for it for sure.
Super potato has walls of pc games, but as any other retro-only shop who deals with that stuff for a living, isn't the most cheap one. but still, if you like to get the good stuff and you wanna get it right now, this is your place.