I do remember hearing that several EK A380s are lined up for NRT. I was already surprised, since cities getting the A380s would be already 'proven' for EK (e.g. LHR, SYD etc.) whereas Tokyo would get the A388 on the inaugural.
It seems that the problem at NRT is slot-related-if they can fill planes from Nagoya and Osaka, then they can surely fill planes from Tokyo.
Currently, EK departs at 02h35 for Osaka, arriving at around 16h00 and heads back for Dubai at 11h15 arriving at around 05h00 in time for the European departure bank.
More or less the same for Nagoya. So you're right flyboy777-NRT would see the same thing.