The Great War spread across the world quite rapidly. It wasn't really surprising when you really thought about it. After all, the majority of the world was currently owned by the Great Powers. There were few independent nations outside of Europe that remained.
However, one of those independent nations was the Empire of Japan, and they were perhaps the only non-European nation in history who had more or less kept up with the level of development of the European Empires, so much so that in the first half of the 20th century, they were capable of challenging them to some degree.
Something that nobody else on the global stage was really remotely adequately prepared for. It was true that by 1945, Japanese technological development had completely and totally lagged behind their allies and rivals on the global stage.