I'm going for 5 mo soon (inc. Japan...no idea if the name is a coincidence) and have no intention of getting the jab.
IF there is a real point to getting it, and you realize that once there, it'll be readily available and probably a tenth of the price. If it isn't, it's just another jab for paranoid white people :-)
Make sure you have the 'standard ones' - HepA, Typhoid, Tub etc. They should be free and are likely to be boosters to the jabs you had years ago.
I also got HepB (in case i end up in A&E for any reason...) and Rabies (useless unless you are heading WELL off the beaten track. It just buys you another 24h). I probably wouldn't bother if i had to do it all again.