Japanese failure to develop new weapons as the war evolved
When Japan attacked the United States at Pearl Harbor they had in their arsenal one of the most advanced fighter planes in the world, the famed Zero. They also possessed weapons which were technically superior, and their warships carried flashless powder, enabling them to engage in night battles at sea, as they did in several battles in and around the Solomon Islands. The Americans often found their battle lines illuminated during these engagements, leading to the loss of several ships in the battles fought during the Guadalcanal campaign. The US rushed to develop competing technology, including better fighter and torpedo planes, and superior tactics.
Over the course of the war the Japanese failed to develop improved aircraft and other weapons, and somewhat quickly lost the technological edge to the Americans. The Japanese, deprived of oil and other raw materials such as rubber in their home islands, found their empire under pressure from American submarines and air strikes which destroyed their merchant ships and tankers. The failure to develop new weapons using the technology which emerged during the course of the war, which is a factor of most extended wars, was a critical mistake for the Japanese. By the end of the war the Japanese were fighting with mostly obsolete weapons and equipment, using the tactics of fighting to the death, which their own planning made all but inevitable.