Because in order to become a world power you need to over throw and defeat the current world power. So the US was in power, so Japan wanted power, so they decided to try to attack and defeat.
Japan
Japan was already a major power by the mid 1890s. In 1904-05 they inflicted a humiliating defeat on Russia in the Far East.
The military defeat of Germany culminating in the Suicide of Hitler & Atomic power in the war against Japan
They democratized and rebuilt their economy with breathtaking speed. Japan's rapid postwar recovery from the ashes of total defeat lead them to become the third most powerful economy in the world (after the US and China).
The allied powers.
Japan gave up after Germany lost the war.
It was considered as the first great war of the 20th century and It transferred the power to east asia
An increase in manufacturing.
Island hopping
To the defeat of Japan.
Japan was a rising power in Asia in the early 1900's. Following their stunning defeat in 1905 of the Russsian Navy at the Battle of Tsushima, Japan's military was quickly recognized as world-class. The Japanese worked this backward and continued to build and improve their steel mills and other industrial manufacturing, plus increased educational opportunities. They took advantage of the distance from the United States and the UK to become a local Pacific power.