Hirohito didn't make a speech or address, but he sent out an official announcement to the military and to Tojo that Japanese civilians should commit suicide rather than be taken prisoner.
As the war turned against the Japanese, Hirohito personally found the threat of defection of Japanese civilians disturbing because there was a risk that live civilians would be surprised by generous U.S. treatment. Native Japanese sympathizers would hand the Americans a powerful propaganda weapon to subvert the "fighting spirit" of Japan in radio broadcasts. At the end of June 1944 during the Battle of Saipan, Hirohito sent out the first imperial order encouraging all Japanese civilians to commit suicide rather than be taken prisoner.
The Imperial order authorized Lieutenant General Yoshitsugu Saito, the commander of Saipan, to promise civilians who died there an equal spiritual status in the afterlife with those of soldiers perishing in combat. General Tojo intercepted the order on June 30 and delayed its sending, but it was issued anyway the next day. By the time the Marines advanced on the north tip of the island, from 8–12 July, most of the damage had been done. Over 1,000 Japanese civilians committed suicide in the last days of the battle to take the offered privileged place in the afterlife, some jumping from "Suicide Cliff" and "Banzai Cliff".[
Before the eventual unconditional surrender of Japan after the dropping of the atomic bombs, the government was considering orders for mass-suicides "modeled on the 47-Ronin incident."
By the time Japan surrendered, 10,000 civilians are believed to have committed suicide. Many in the military also committed suicide by crashing planes into American ships. 3000 Japanese sailors were found aboard one ship who had all committed suicide rather than be taken prisoner.
The information sourced here is mostly from Wikipedia. I suggest the book "Girl with the White Flag" (white flag for surrender) for a personal historical account of the absolute terror Japanese civilians felt when American troops approached. They believed the soldiers would brutally murder them.
This wasn't the account of Japanese history I learned, so I read more up on this. The information can all also be found on Wikipedia. I learned that the Emperor had very little role in the war, but this is apparently was a fabrication by the US to exonerate him from war crimes. The best and newest evidence shows he was intimately involved. The US did this perhaps to make Japan easier to govern and occupy, as the emperor had an important symbolic role to the Japanese people; and also, the US put all blame on the military, therefore discrediting them. They told the Japanese that they and the Emperor had been tricked by the military. Hirohito offered to stand trial for war crimes and the US refused to allow him to do this.