As well as on their side. The bomb probably saved even more Japanese lives than American lives.
There's no "probably" there. Between an invasion and the continuation of our destruction of Japan's internal transportation system, the Japanese were looking at catastrophic casualties, both civilian and military, if they had not surrendered. They were already on the brink of famine in late 1945 due to a combination of a poor harvest and their inability to transport what food there was to the population centers.
Surrender was the best thing that could happen to the Japanese. If it took the a-bombs to shock them into it, so be it.