Direct TV is a company that want to make profit from the service they offered.
There are 2 suggestion for you:
1. Write a request letter to them to have japanese station and wait for their updates. If they have huge similar demands, sure they will consider to open Japanese station, just like spain channels.
2. Try to look for same group of people that have the same wish as you and post your request to Direct TV at same time - I think they might willing to consider your request.
