Default [Q] Japan Sim Card

Hi,

I'm heading to Japan in about a month's time and have a Nexus 5. I'd really like to be able to use my phone over there. Does anyone have any experience with Sim cards in Japan?

I've heard there might be 1.5GB pre-paid sim available from somewhere at Narita Internation Airport.

I dont' need voice, just data - for google maps etc.

Does anyone have any experience with this? Would my phone work on a 3G network over there?

Any help or advice would be appreciated.
ROM: Changes too often
Phone: Diamond -> iPhone3GS -> Touch Pro -> Desire -> iPhone4 -> Transformer Prime -> DesireHD -> HTC One X -> Galaxy Note 2 4G + Nexus 7 - > Nexus 7 (2013) -> Sony Xperia Z + Nexus 5 + Samsung Note 10.1 2014 Edition