There was a 5.9 off the coast of Fukushima that I felt pretty good here last night. If you're interested in checking it out I use this website sometimes after feeling a tremor.
http://www.jma.go.jp/en/quake/
It's from the Japanese Meteorological Agency - in English. They have their own separate scale here that goes upto 7, which is what this site uses.
The newer cell phones are wired into the early warning system here. It's not an app that you would have to buy separately. There's a crazy siren sound that goes off if a bigger earthquake happens close to your area. I can't remember exactly how big it has to be to trigger the alarm.
I bought a new cell here after the big quake, and the first time that alarm went off it scared the crap out of me. Wasn't sure what was happening, or where the alarm was coming from.