If you want a cheap flight from Hong Kong to Tokyo, you've got zero airlines to choose from.
Make sure you use the search options above to search for flights to other airports in Tokyo, not just New Tokyo International Airport. The more options you look at, the better your chance of finding a cheap deal.
If you're planning on going to Tokyo during this time, you could take a look at other airport options. Or you could try to get a last-minute bargain.