It is a reasonably well-known story that when the Pacific War began, a lot of people felt refreshed, felt clean and clear.
The war with China had dragged on since 1937, the Imperial Rule Assistance Association was founded in 1940, controls on goods went into full force, newspapers were merged, and so on — before the Pacific War began (December 1941), a heavy, oppressive air had spread through Japanese society.
People knew from the news that the Japan-U.S. negotiations were still going on, so they were irritated by not being able to see what lay ahead: "how is this going to end up," "when is the war against America and Britain going to happen."
There was another thing. The war with China had gone on so long that its cause had blurred. The war against America and Britain, by contrast, had a simple, clear purpose — break the ABCD encirclement — and that was easy to understand and exhilarating.
Tokugawa Musei left a record of his state of mind in this period in the preface to *Musei's War Diary* (Musei senso nikki).
There was truly not a single day when my nerves were at rest. We had, in today's language, become neurotic. I could not bear any more days of that kind of tension. And into that came the Pacific War of December 8. Whatever else it meant, now it would be settled one way or the other. It was a feeling of "well, at last."
And then the war began, and a great many people felt refreshed.
A boy in the Imperial Rule Assistance Youth Corps heard the news of the war's outbreak while he was doing radio calisthenics, and ran flying home, skipping and screaming, "They did it! They did it, it's war at last!" There is a very grade-school kind of stupidity to it, quite likable. 『Reading and Talking About 8·15 (Hachi ichigo o yomu kataru), Nihon wa Kore de Ii no ka Shimin Rengo, Daisan Shokan, 1982』
When a newspaper reporter from the Goshogawara branch office called on a school principal for an interview, he was told out of nowhere, "They've finally done it, I feel cleared out (sappado — dialect for sappari)." When the reporter asked, "What do you mean?", the principal said excitedly, "You don't know yet? The Japanese forces attacked Pearl Harbor and won a great victory. War with America at last. We have declared war." 『The Toou Nippo and the Showa Era, Part One (Toou Nippo to Showa jidai zenki), Toou Nipposha, Toou Nipposha, 1979』
At a sanatorium for wounded veterans, a patient who heard the news shouted, "Hey! War with America!", and T, hearing it, all but threw himself at the radio by his pillow and switched it on. "Ah, they did it, they did it. They've finally gone and done it," thought a man named Numata as well, but he wept over his own uselessness, unable to stand on the front line because of his injuries... so it says, though what he really felt is a mystery. He may well have been thinking it was rather lucky he was wounded. 『[The Rustle of the Wheat Ears: Essays by Wounded Soldiers (Mugi no hozure: shoi gunjin zuihitsushu), Maemoto, Kazuo, Nihon Bunshosha, 1943 1943」(https://dl.ndl.go.jp/pid/1110054/1/110)』
A woman office clerk who learned of the war's outbreak at her company felt something ring out bravely in her breast. "Everything before my eyes cleared away at once, and even the cold that stung the eyes felt refreshing that morning." The men were "all smiling, saying to each other, we did it, we've done it, worked up as if they themselves were going off to the front this very minute," and her colleague Y whispered, "The men all look so happy, don't they." 『Shintenchi 23(1), Shintenchisha, Shintenchisha, 1943』
Sato Kiichiro wrote that "the people, who had endured and restrained themselves for so long, had come to see that any further patience was a hair's breadth from humiliation, and were staring at the government's bag of forbearance with two hundred million eyes — and at just that moment, at last" the war began, so he felt "the refreshed feeling of having a swelling, spreading lump cut open by surgery." "People must surely have felt, 'There it is!', as if the long-awaited moment had come." — but this cheerful obliviousness is close to the schoolboy introduced at the start. 『Buoys of the Town: Essays and Criticism (Machi no fuhyo: hyoron zuihitsushu), Sato, Kiichiro, 1901-1970, Sensei Shoten, 1943 1943』
One thing to keep in mind is that these feelings are not necessarily what the writers really felt. Anything written during the war would have taken censorship and public reception into account. This next one, for instance, is surely typical crowd-pleasing propaganda.
"We'll win!"
The sturdy spirit of the Yamato soul boiled up until you could all but hear it.
(passage omitted)
The report of the war's outbreak was broadcast at once by radio into every corner of the country. The whole nation kicked off their bedding and sprang up. Adults and children alike rushed to their radios. The radio cried out over and over:
"Before dawn on this eighth day, the Imperial Army and Navy entered a state of hostilities with American and British forces in the western Pacific."
Repeated again and again. You could feel, ringing through it, the tightened resolve even in the announcer's voice.
"It's war."
"They've done it."
"We've won. As if we could ever lose."
The hearts of the whole nation became a ball of blazing fire and flared up all at once.
『[The Story of the Great Japan-America-Britain Decisive Battle (Nichi-Bei-Ei daikessen monogatari), Wada, Masao, Tsuru Shobo, 1942] National Diet Library Digital Collections ↗
Against that, in 『Shintenchi 23(1), Shintenchisha, Shintenchisha, 1943』 Miyake Toyoko writes plainly: "My emotion was truly a childish, simple thing, but my feeling now is that I cannot think lightly of that childish, simple emotion. I wanted to value precisely the self that could follow such simple emotion honestly." There should be no lie in this feeling. This is how I have chosen the ones that seem, on balance, more trustworthy.
As for what was written after the war, the number of people who want to say "I thought the war was a mistake" goes up, so the reliability is low. Intellectuals are especially unreliable, and any number of such intellectuals turn up in Murakami Hyoe's "December 8, 1941, on That Day...". Note, though, that reading this requires registration.
So I cannot assert that the feelings introduced here were the feelings of the time. Even so, my impression is that there must have been a great many people who felt refreshed, who felt clean and clear.