Nobody has bothered writing a review for this movie, so I suppose I will.
From Nakazawa Keiji, the creator of Hadashi no Gen (Barefoot Gen) and Kuro ga Ita Natsu (Summer with Kuro). Kuroi Ame ni Utarete (Beaten by the Black Rain) follows first and second generation survivors of the Hiroshima bombing. It's easily Nakazawa Keiji's most resentful film.
The characters in this movie have a very low opinion of Americans, and the people who made this movie don't project a flattering depiction of Americans. The characters have no outlet for all of the negative emotions they experience, so they try to get revenge on oblivious tourists
by doing morally reprehensible things. They're acutely aware of how irrational and unfair they're being; they can't move on from their experiences due to heavy discrimination against atom bomb survivors.
Ultimately this movie is the manifestation of all the pent-up bitterness and resentment that atom bomb survivors had for the inescapable circumstances that surrounded them in post WWII Japan. The Japanese government and the Japanese people failed them, and Americans were oblivious to their struggles. It's a bit of a downer, to say the least. The movie doesn't vilify or justify the actions of its characters. It leaves judgment up to the viewer. Some of these people behave terribly, some try to move on, and several of them die regardless of what they were doing.
It's a polarizing movie. Some people will appreciate it, most people will see it as a pointlessly hateful and ugly movie. I'd recommend seeing it despite any preconceptions you might have. If nothing else, this movie has convinced me that atom bombs are far more destructive than we think they are, and they have destroyed far more lives than Wikipedia gives them credit for. The purpose of this movie is to showcase the terrible things atom bombs can do, and I think it succeeds in that endeavor.