All pocket wifi devices come with instructions on how to use them, battery charger, wallet to carry it and a prepaid envelope to return the device before you leave Japan
If finding the wifi network and password is not evident to you, do not worry, all you need to know is:
To access your pocket wifi password:
- Swipe up the screen
- Touch "SSID"
- The first one is SSID (the name of the network that you will choose) 2nd one is Password
Once you have located the name of the network and password, you are good to go. On the instructions SSID is actually the network and the password comes with the rest of the information, your phone should be able to connect to the network if the device is on and fully charged