Great article! I came across this in my research for our trip to Tokyo and had been really nervous about it. I think that's why we bent over backward to mimic what the other Japanese patrons did so we wouldn't be the obnoxious American tourists. Frankly, since we're of Chinese descent, I also wanted to make sure we weren't fitting the stereotypes of obnoxious Chinese tourists either.
I saw one couple presumably from China (since I understood their conversation in Mandarin) who spent the entire meal at a high end sushi bar surfing on their phones. They took photos of the food, inhaled the nigiri, and then went back to surfing. At least they didn't take any calls while at the sushi bar!
It seemed the absolute height of rudeness and we were so embarrassed to be seated next to them. We deliberately kept our phones in our pocket/purse because we didn't want them to see 4 of the 6 guests with phones out!