The US Occupation of Japan (1945-1952) was carefully run in order to encourage positive US-Japanese relations after the mutual antipathy of World War II (which involved far more than just the atomic bombings). This included positive things like aiding in the rebuilding of Japan, and more negative things like censoring anti-US sentiment.

But to your question of specifically the atomic bombings, a survey done in 1947 (which I discussed awhile back) revealed the following attitudes:

Less than one-fifth of the respondents in Hiroshima and Nagasaki expressed hatred of the Americans for using the bomb. Typical of the expressions among this group are the following:

They really despise the Americans for it; the people say that if there are such things as ghosts, why don't they haunt the Americans?

I only wonder why they did not let the people know of this bomb and give us a chance to give up before bombing us?

After the atomic bomb exploded, I felt that now I must go to work in a munitions plant . . . My sons told me that they wouldn't forget the atomic bomb even when they grew up.

I didn't know about the atomic bomb before. After the bomb dropped I thought it was terrible. I think that it was cruel to drop those in an area where ordinary people are living. I don't see why they didn't drop it on some army camps or something.

The proportion of respondents in the atomic-bombed areas who expressed hatred because of the atomic bomb is greater than the proportion in the rest of Japan who expressed hatred because of bombing in general (approximately 19 percent as compared with 9 percent). These figures probably underestimate the extent of hostility, for several reasons. No doubt one of the factors involved is that many Japanese, out of fear or politeness, did not reveal their feelings with complete candor to American interviewers.

It is also possible that people's subsequent attitudes served to color their reports of their experiences at the time of the bombing. The interviewing was conducted three months after the surrender, at a time when Japanese war leaders had become completely discredited and American prestige was very high. Many of the respondents, for example, were hoping that the Americans would supply them with food, so hostile attitudes expressed to American interviewers would be extremely inappropriate. There is evidence that the hostility was turned against their own government. In response to the question, "When the American planes bombed Japan, on which side did you feel the responsibility lay?" 35 percent of Hiroshima-Nagasaki area residents stated that it was Japan's fault. This percentage is much lower, however, than the percentage of people in rural and urban Japan who gave this same response (45 percent and 47 percent respectively).

During the postwar Occupation, very little discussion of the atomic bombs was permitted in the Japanese press, and the atomic bomb victims (hibakusha) were shunned. So there wasn't as much "processing" as you might expect (and no polls to my knowledge). This is one of the reasons the Japanese were so angry by the Castle Bravo accident, which re-opened the atomic bomb issue for them not long after they had re-gained their independence, and served as a sort of proxy issue to talking about the atomic bomb attacks.

Further discussion: Asada Sadao, "The Mushroom Cloud and National Psyches: Japanese and American Perceptions of the A-Bomb Decision, 1945-1995," Journal of American-East Asian Relations 4, no. 2 (Summer 1995), 95-116.