[RobinMask]

Like others have said it's too soon to tell. The UK government site says that some flights to Narita have begun again, but there is no public transport to and from the airport. There is also still a risk of tsunamis and aftershocks. Whether this will still be the case in a fortnight is yet to be seen, but I would personally contact your travel agent (or whoever you booked your holiday with) and see what they say.