Having a very difficult experience on our last trip to Japan without speedy internet (our mobile service provides 128k service for free, but it's good for nothing), I purchased a mobile wifi cellular hotspot (4g/LTE Netgear Unlocked mobile hotspot) and this Zen Simcard with the hopes of having speedy cellular internet upon landing in Japan

Once activated, Between Downtown Osaka, Universal Studios Japan, and Miyajima, my internet "fast" internet service did not exceed .5Mbps