The correct answer to this open question is the following.
Although we have not read the documents you did, we can help to answer this question based on our knowledge of the topic.
Japanese Perspective: Why wasn't it necessary to use the bombs?
The Japanese point of view of throwing the atomic bomb over Hiroshima and Nagasaki is the following. Japanese people said that was a terrible military action that caused too much pain. suffering, and destruction to Japanese civilians. Japan considered was an unnecessary action on the part of President Harry Truman. Many Japanese think that the action had to be punished as a war crime. They say that strong military action such as conventional bombing over Japanese strategic places and a series of blockades could be more than enough to force Japan to surrender easily.
Of course, this is an issue that had caused so much debate not only in Japan but in the United States as well.