If you want data, I highly recommend renting a wifi hotspot. It lasts all day and lets you connect multiple devices, so as long as you and your wife are together you'll both have internet (try to establish rendezvous locations beforehand in case you lose each other, or getting something like Tile to help you reunite).
I've done data sim cards before, but my experience with the hotspot has me converted.
Rental Mobile Wifi Mifi Pocket Wifi in Japan, Portable Wifi Mifi router access point:: Global Advanced Communications
I used these guys for my last trip, the hotspot was waiting for me at the airport and three weeks later I dropped it off in a post box with the pre-labelled package at the airport on my way back out. Pretty flawless experience, altogether.