I don't know if DEN would be a good idea. There would be no feed there, and the flight would be so long that it would require two aircraft to operate. Also, I am not sure who would like to travel there except tourists who want to ski, and I think most Japanese go to the Japan Alps & Hokkaido for that. And Japan Airlines doesn't even codeshare with any airline to Denver. Maybe it will be possible once JAL gets their new 777LRs, but I think JAL should concentrate on other cities that may need their service, like Seattle or San Diego, or maybe a flight from Osaka to San Francisco.