From what I heard (but I am no expert at all) Japanese culture encourages an extremely sharp (at least from the standpoint of Europeans and I would guess Americans) separation between business and private life, e.g. behavior which Europeans would consider highly eccentric - say a high powered banker running around disguised as Mickey Mouse in his off time - are considered a non issue.

In case this is true, this could be a reason why Japanese people don't really see much of a need to ensure that an online identity can be traced to "real identity", because they consider the "virtual identity" to be "good/real enough".