Actually the reasoning of the Japanese military junta from the time they took power in the early 1930s was really bizarre, from our perspective now.
Admiral Tojo, the zaibatsu industrialists, and the others of the junta came to power around 1932, and one of their concerns was Communism and the possibility of invasion from the Soviet Union. This wasn't wholly unrealistic. The world watched the USSR under Lenin invade Poland and the Baltic States in 1925, and only vast amounts of French and British military aid through the League of Nations was able to turn the Red Army back from the gates of Warsaw. Stalin came to power and began making threats against Finland, which he made good on a few years later, and also demanded that Japan give him the island of Kita-Ezo, which is now called Sakhalin.
So, Tojo and the junta were, perhaps justifiably, scared shitless of what Stalin might do, and they thought their first priority had to be building up their military to resist an invasion. But they didn't have the industrial base or resources for it.
So Tojo made what turned out to be a Very Bad Decision: invade China (which was at the time in a state of chaos and anarchy, with no functioning central government, just warlords and bandit armies), set up a puppet government, and use the population as slave labor to mine coal and iron, and grow rice and wheat, and ship them back to Japan.
This gained the attention of the US, which Tojo and the junta didn't really expect. They didn't think the rest of the world gave a shit about China. They thought that if the US cared enough to do more than just talk, the US would have tried to help one or another of the stronger warlords to create a government to restore order. However, from the end of World War I on, there had been a fad in the US (more specifically, among the wealthy East Coast intellectuals who controlled American newspapers and radio) for Chinese food, Chinese games like mah-jong, Chinese style silk dresses for their wives, and what-not. And these people looked at the Japanese invasion of China with horror and rage. Hitler and the Nazis weren't thrilled about it either, because they were very good buddies with a Chinese bandit king named Chiang Kai-Shek and they were selling lots and lots of rifles, ammunition, artillery pieces, armored cars, and light tanks to Kai-Shek's army and even had German advisors in China training Kai-Shek's troops, but that's a story for another day.
Anyway, America had pretty much ignored the equal or worse horrors of Kemal Ataturk's war of extermination against Turkish Armenians, Christians, and Kurds going on at the same time, but the owners of the newspapers, radio stations, and newsreel companies fed Americans a steady diet of atrocity stories from China (at least half of which were true) for years, and popular anger against Japan lead directly to Roosevelt ordering a trade and oil embargo against Japan in 1939 or 1940. Yes, the US exported petroleum back then.
Anyway, the US had been up until that moment one of Japan's biggest and most important trading partners, and this hurt the Japanese economy very badly. Tojo believed, again, that it was just talk, and that a show of force, maybe a raid on a military target like the naval base at Pearl Harbor, would cause the Americans to realize the seriousness of the matter and quit screwing around.
This was one of history's bigger mistakes, I think. One can imagine a parallel universe in which Tojo and the junta took a more subtle approach, maybe making some kind of deal with Chiang Kai-Shek themselves to help the Germans prop him up as a local puppet. Without having drawn US hostility, the Japanese would have felt no pressure to join the Axis and been neutral in World War II or perhaps even joined the Allies at the last moment, when it was obvious who was going to win, like a lot of opportunistic South American countries did.