You can fly on United from LA to Tokyo, nonstop, for as little as $721 RT including tax.
We found seats leaving May 16 and returning May 21, 22 and 23. Can't get much more last minute than that.
For $40 more round-trip, many other days are available, such as depart May 28 and return June 6. All other airlines are charging about $200 more for this route nonstop. Seats are limited at these low United fares. Book them on Orbitz.com using a flexible date search.
From San Francisco, we found a one-stop via Seattle on United leaving May 21 and returning a week later for $768 RT. Every other airline was charging at least $1000 RT on those dates.
From Seattle, Northwest has nonstops to Tokyo for just $701 RT for May and June travel. A wide range of dates is available. Other airlines are charging much more.