The early evening in Tokyo was hot (83° F) and steamy, and one of the world's busiest air terminals, Haneda, was even more jammed and uncomfortable than usual. But most of the jostling travelers were in a festive, uncomplaining mood. The three-day observance of Bon, a holiday season nearly as joyous as New Year's, would begin the next morning. Many Japanese would devote the days to nostalgic visits to the places of their birth, to happy reunions with relatives, to paying homage to their ancestors. The more religious among them believed that the spirits of their forefathers would return to the family sites too and join in celebration with the living. But for 520 people who boarded Japan Air Lines Flight 123 bound for Osaka, the trip would be tragically one-way: before they could honor the dead, they would join them.