This particular film is centered on very ironic bases. First, the particular score of the film gives the overall tone a very ironic feeling. In the beginning of the film, the remains of Hiroshima are shown in a very documentary-like style. During these shots of debris, burned down buildings, people being trapped and being forced to break out, severely burned victims with their bodies being reduced to bones and scars, the nondiagesis is relatively light-hearted for something that has become so devastated. The use of these shocking images also adds a sense of shock value to the film. The story itself is also relatively ironic. The audience is introduced to the two lovers in the film during the description of war-torn Hiroshima. The contrast between their skin rubbing against each other and the destruction of the city is very vivid.
It's also very ironic that there are so many tragic stories being told in the middle of a tragedy. Granted that the war is over, the memory and the impact that it had on Hiroshima is very prevalent throughout the film. It is very interesting that not only is this love affair just that -- an affair. But this mutual love and admiration is also brought about by war. They even feel as if they should decide to leave each other, they will only be brought back together by another war. The ambiguous ending of the film only echoes this sentiment.