Earlier quoted context omitted.
There appears to be a fine line between "business" (meetings etc) and actually doing productive work for a company entity based in Japan. I don't have clarification on this, and this is only second hand information. On a different note, they do check the frequency of re-entries (on a tourist visa) as I know of one peer who was put into a room at the airport and questioned after re-entering a few times in one year. So…
I'll take your word for, I've only ever entered Japan as a tourist and they really don't look that closely at Americans entering Japan for tourism.
If you read blogs on these types of things you are only going to see the 'worst case scenarios' as the majority of people with positive experiences are unlikely to rush to their PC and write a glowing post about their Visa experience...