I was with you, up until Japan. I don't know where in Japan you live, but I have not found one location yet that people won't use a cell phone. Train, basu or restaurant? Fine with me, it's the cars, motorcycles, and bicycles that scare the hell out of me.
People on cell phones drove me crazy in the U.S. but Japan has taken mobile-distraction-while-operating-machinery to a whole new plane. I'm one of the few people who wear a helmet while riding my bicycle (a skate/snowboard helmet) and I get all kinds of scoffs for it, but 7/10 of the foreigners I talk to here have been hit by a car on their bike (thankfully nothing serious yet) and 4 of them they felt were because of mobile distractions.
Japan has so many fantastic social rituals that make things generally pleasant, but the cell / keitai are not part of that.
The worst part about it is that most of the time people aren't talking, they're texting! Not even looking near the direction they are going! Crazy. Try texting someone while riding a bike in the rain while holding an umbrella and a can of coffee with headphones on, it's the norm in Japan (and will be, for a few generations).