Japan Airlines, the oneworld carrier, is offering 50,000 roundtrip economy seats on domestic routes for free. The offer is open to anyone who will be in Japan between June and October.
It is a bit of a lucky dip. The flights are only available from Tokyo Haneda and Osaka. Once you register your interest and departing airport, you will receive an email within 3 days confirming your destination.
There are a few requirements in order to take part:
You must have an international flight to Japan between 1st June and 31st October, although your free flight will only be for July, August or September
You must have a JAL Mileage Bank number
You must not be a Japanese passport holder (or if you are, have permanent residency in another country)
If you do not already have a JAL Mileage Bank account (and you probably don’t!) it takes 5 minutes to sign up on the JAL website here.
The free flights are being offered from 1st July until 30th September. During the application process you can choose from between three and five departure slots per day. You are then shown four possible destinations, of which one will be confirmed by email within three days.
You can apply for up two four people. JAL is accepting 250 applications per day, so you may have to try a few times before you get to the application page.
The free flights are for economy tickets only, although you can pay for space-available upgrades to business class or first at the airport. If your plans change you can cancel for free up to two days before departure, although you may not re-apply for the promotion. If you cancel within 48 hours, you may incur a cancellation charge (check the Ts&Cs yourself – it isn’t 100% clear!).
ANA is also running a special promotion for foreign visitors, although it is not offering free tickets. You can see the details here.