Last month, as they have every year for decades, a small crowd of people gathered under fat cherry blossoms in Tokyo's Aoyama Park, carrying red lanterns, placards and peace symbols.
From a distance the gathering could have been a hanami party, but the perfumed spring air is soon rent by angry speeches directed at a site behind the park boundaries: an elevated U.S. military heliport flanked by several squat buildings.
Amid the speeches, a U.S. helicopter clatters low overhead, drowning out the protests and showering the group with cherry-blossom petals. "Look at the size of that thing," shouts one protester above the din. "What if it fell onto a school?"