The largest network coverage! Usable in various places, even in subways!
docomo's mobile Wi-Fi uses their network, which covers the largest areas in Japan and is stable and consistent. With their network, you can connect with the internet even you are in buses, trains, and subways.
Although they don't offer any unlimited data plans, considering using it mainly for SNS or Google Maps, their offerings are just sufficient for your needs.
Unlimited data, recommended for use in urban areas!
Y!mobile offers a service called unlimited data advanced mode, which is available only with devices compatible with it.
It enables you to connect with the internet without worrying about the data capacity and the transmission speed. Although the service does not available in many rural areas yet, you can use it in urban areas without any problems.
Regular mode covers area wider than that of with the advanced mode, however, if you over the data capacity of 7GB, the transmission speed decreases to 128kbps.
Note that if you change the mode to the advanced in that situation, the speed does not be changed until that month is over.