As a student of WW2, millions of Japanese lives were saved by the atomic bombs:
1) Japanese military leaders were planning to continue fighting until no citizens were left: "even if the Japanese people die, their spirit will live on."
Surrender rates in previous island battles were on the order of 1% (ie. 99% killed or seriously injured.)
2) the Japanese people were facing starvation had the war continued. The early surrender helped with the rebuilding effort and prevented the nation from literally starving to death.
3) American leaders chose to bomb secondary cities, rather than completely destroy Tokyo, a capital city
4) had Russia invaded Japan, they typically would de-industrialize the enemy by transporting power plants and other facilities back to Russia
5) Japan actually refused to surrender to the USA. The emperor's broadcast never used the word, and the leader who signed the surrender document was approx. #10 in the leadership hierarchy.
The emperor was a serious amateur microbiologist and realized what an atomic bomb was, so did not need convincing that the war was lost.
(He was against starting the war with China and the USA and said so, but faced assassination and constitutional issues if he made a serious effort to change sentiment.)