While in Japan you may want to call home. Having a phone will ding you with expensive charges and renting a phone in Japan will so the same. so, what do you do? you get Skype. Using skype you can call home for a lot less than with normal phones. With an unlimited data plan mobile hotspot you can call from anywhere. one other thing you can do is video call someone and show them things on your trip as well. please be respectful when doing this.

iPhone: https://itunes.apple.com/us/app/skype-for-iphone/id304878510?mt=8
iPad: https://itunes.apple.com/us/app/skype-for-ipad/id442012681?mt=8
Android: https://play.google.com/store/apps/details?id=com.skype.raider&hl=en