Actually, there is a quite interesting, mind-blowing relation between Japanese Imperialism of the 30s and a certain sect of Japanese Buddhism, that starts with the Mongol invasions of Japan and ends with a hare-brained Colonel, his "Final World War" agenda and the creation of the puppet state of Manchukuo.

Let's start in the 13th century. It's the Kamakura period in Japan, and the Japanese people are really nervous. They have been the targets of two massive expeditions by the world's most potent fighting force of the time - the Mongol Empire. Commoners think the high-up Buddhist monks holed up in their mountain temples are corrupt, and they're not wrong, frankly.

In comes a guy called Nichiren(日蓮). He's a monk also, but he's not like the rest. He's radical. As in super, super radical. Nichiren rejects all previous teachings except this one book called the Lotus Sutra(法華経), or Nam-myoho-renge-kyo. In this book, Buddha teaches that ALL beings, regardless of their status could achieve 'true learning' and become Buddha. With no restrictions at all. Anyone, whether he's the Shōgun himself or a mere peasant grovelling in the dirt, could become Buddha.

Not only that, Nichiren was radical because he said he alone was the right teacher during the coming Age of Degeneration(末法), or mappō, which he equated with the Mongol invasion. It's sorta like the Apocalypse, or the nearest thing Buddhism has to the Apocalypse. All other sects of Buddhism were useless in his opinion, and the country of Japan needed to embrace Nichiren's thought, and that sect ONLY in order to thirve in the coming new age. You can get why he wasn't popular with many monks.

But Nichiren was also a teacher as well as a scholar, and he educated many disciples, who set up the branch of Nichiren Buddhism(日蓮仏教).

Fast forward to the Meiji era. There appears a Buddhist scholar, named Tanaka Chigaku(田中智學). Now, Tanaka is a preacher of Nichiren Buddhism. BUT, he is also a fierce nationalist. And he finds a way to combine his religion with his ideology, and fuses Nichiren Buddhism with Japanese Nationalism, especially the notion of Kokutai(国体). The result is a new interpretion of Nichiren Buddhism called Nichirenism(日蓮主義).

Now... things begin to get weirder and weirder.

Tanaka says that the Mappō Age preached by Nichiren is actually a clash between the Asian Civilization and European Civilization. This massive clash of civilizations was supposed to be the "Final World War", between East and West. And Japan was going to come out on top after all the fighting, and organize peace between the various combatants. In the end, the Japanese emperor, or Tennō, would rule over a unified, harmonious world.

I'm not kidding, he really was a nutjob. The phrase Hakkō Ichiu(八紘一宇) - a famous WW2 Japanese slogan was actually coined by Tanaka in this context. That the emperor's moral leadership would encompass the whole world.

Tanaka formed a society called Kokuchūkai(国柱会) to propagate Nichirenism. And a Japanese Army officer by the name of Ishiwara Kanji(石原莞爾) joins this society. And he actually believes in this... well, nonsense. And he writes this book called "An essay on the Final World War"(世界最終戦論). In this book, Ishiwara states his firm belief in a ultimate Japanese triumph in the coming war between East and West, for which he even had an exact date - 1966. The reason? Tanaka said that "All the world will follow the teachings of the Lotus Sutra in 48 years." He said this in 1918. 1918 + 48 = 1966. Wow muh logic.

Now this would all have ended with a couple of nutjobs yammering on, if not for the fact that Ishiwara was also an officer in the IJA. An army that was disgruntled by not gaining anything in Siberia during their most recent excursion during the Russian Civil War, being looked down upon by civvies, and constantly being at odds with the Navy. Add to that the social disturbances of the Great Depression, and Japanese Militarism definitely begins to rear its ugly head. Ishiwara was a colonel in this army, posted as a staff officer in Manchuria.

And he begins to spout rubbish, like this piece of writing in 1927. "Shōwa 2. While I was praying at the Ise Grand Shrine(伊勢神宮), I saw the Kokutai shining with light. I talked to much-esteemed Lt.Col Saeki about this, and his response wasn't that positive so I decided to tell no one else."

Later, when Ishiwara was fired(he wasn't that great pals with Tōjō), a schoolteacher thought it might be a good idea to drop by and have a chat with the retired general in 1943. Since Ishiwara's "Ise Vision" was published in his 1940 essay, the teacher was curious about what it meant. When asked, Ishiwara revealed his full vision.

"The Earth's Globe showed its shape and a golden shaft of light shined from Japan to Manchuria."

About the Final World War again. It's obvious(in Tanaka and Ishiwara's mind) that the side leading the "East" will be Japan. Now, who could be the "West"? The U.S of A, of course! But Japan is severely outmatched by the US in sheer power - no-one in Japan believed otherwise, not even the guys who ordered war against the US in 1941. So, in order for Japan to come out on top in the "Final War", Japan would need to seriously beef up on size. So how could Japan become greater? That was Ishiwara's question on the way to Ise. Now, Ise had rewarded him with a vision - a light shining upon Manchuria. Could the message be any clearer?

So Colonel Ishiwara Kanji and Itagaki Seishiro of the Kwantung Army begin to scheme. They realize the fractured nature of China, with her various warlords presents an unique opportunity for Japan. And the schemers are too high-minded to ask permission for their plot, not from the "weak" civilian goverment, not from the General Staff in Tokyo, not even from their CinC, General Honjo Shigeru.

Boom. Result is the Mukden Incident, and the subsequent invasion of Manchuria. Which paved the way for all sorts of opportunistic officers on their own missions. One example would the Battle of Khalkin Gol. The other would be the Marco Polo Bridge Incident, which started the Second Sino-Japanese War.

So, yeah. TL;DR - you could say that a certain sect of Japanese Buddhism had a profound impact on, and actively supported Japanese Imperialism. Of course, since this is just one sect, there are other Buddhist monks that preaced pacifist ideals in WW2. Even among the Nichiren Buddhist groups - the Sōka Gakkai(創価学会) were inherently against war, to the point when the movement was forcibly disbanded by the Japanese Government during WW2. So not all. But they weren't all against war, either.

Main source is Ishiwara Kanji's various essays including "世界最終戦論" and 「未完のファシズム」(Incomplete Fascism) by professor Katayama Morihide.