Sumo in Fukuoka

I have airline tickets to go see the sumo tournament. Can I buy the tickets at the venue? Or can I trust the buysumotickets.com?

Airline tickets for sumo? Please excuse my ignorance, but I have never heard of such a combination. It is certainly not a standard offer by the sumo association or buysumotickets.com. What airline offers such tickets? I suggest you inquire with them about the details.

Buying tickets at the venue is hit or miss. Buysumo.com is expensive but reliable. If you really want tickets, I'd go with them.

Its depend on the seat type(Box seat, chair seat), but its rare that the weekday ticket is sold out.
But if you want to see final day, you must reserve the ticket.

I work for an airline so I have tickets on ANA which I get cheap, sorry thats what I meant. And thought id use them to go to Fukuoka but wasnt sure where or how to get tickets.

I get it now. As a rule of thumb, the venue sells out on weekends and national holidays (November 23, 2010), but it does not sell out on regular weekdays, when it would be safe to buy it on the day (unless you want to get good seats).

Buysumotickets.com is run by a very motivated person, and I have only heard positive feedback. Note also that the association started to officially sell tickets in English online:
http://ent-sumo.pia.jp/en/sumo11.php