The treatment of Japan at the Paris Peace Conference left its delegates with some resentment, which contributed to the overall postwar anti-Western sentiment that would later become a key aspect in the rise of ultranationalist and militarist elements in Japanese politics. This response shall delve a bit into the "betrayal" of Japan by the Western Powers throughout the First World War, and also focus on their gains and (perceived) losses from the Treaty of Versailles. Let's begin.

The Rising Sun in Paris

"Tensions over the Japanese stake in China carried over into the World War I peace negotiations at Versailles in 1919. Japan joined the peace conference as one of the victorious allies."

- Historian Andrew Gordon, writing on Japanese aims and tensions at the Paris Peace Conference

The quote above touches on several key points which we ought to develop further. Firstly, Japan felt that it had earned a place at the Paris Peace Conference, owing not only to its wartime participation (which, as OP has pointed out, was actually rather significant), but also due to its own status as a world power.

A common thread that existed in Japanese politics during the prewar era - and one that would continue to persist into the interwar years, was a desire to be seen as an equal power with the Western nations. After all, the Japanese had surprised the West with how quickly they had been able to modernise economically, politically, and militarily. They had stunned those same powers during the Russo-Japanese War (1904 - 1905), defeating a supposedly "superior" Western empire. To Japanese politicians and intellectuals, their meteoric rise in the world stage from the Meiji period into the early 20th century was proof of their right to be considered among the "great powers" of the age.

In tandem with this desire to be seen as an equal power, Japanese politicians and citizens resented the rampant racism against Japanese peoples by the Western powers, with the United States in particular receiving much of the blame. Discrimination actually reached a fever-pitch during the First World War, as fears of the "Yellow Peril" dominated American society and government prior to their entry to the war in 1917 (and it lingered even after that). Prime Minister Shigenobu Okuma remarked in a speech on racial prejudice in 1915 that:

"It is, in fact, no exaggeration to say that from its [racial prejudice] satisfactory solution will date the harmonization of different civilizations of the east and the west, thus marking an epoch in the history of human civilization.

If on the other hand, the solution be proved unattainable, one must then forever despair of the possibility of harmonizing the different thoughts and systems of culture of different races. In this sense the importance of the problem is universal."

The opportunity to end this racial prejudice came with the Paris Peace Conference. There Japan had two key goals: firstly to secure its hold over the German leasehold in Shandong (Shantung), and secondly to insist on steps which would eliminate racial prejudice and, it was hoped, force the West to view Japan as an equal global power rather than an "Asian power". Paul Lauren remarks that the Japanese certainly had the cards to play (or so they believed) to achieve these goals.

"Long resentful that their country's stunning action in the Russo-Japanese War had never received the recognition in international politics that it deserved, Japanese leaders now determined that their recent military victories would never be ignored or pushed aside. Startling successes against German possessions in the Far East, occupation of Russian maritime provinces, burgeoning industrial strength, and loyalty to treaty obligations with the Entente would guarantee them a place among the Great Powers at the [Paris] peace conference."

Japan would go on to achieve only one of its aims, and even then those gains would be short-lived. We shall explore that following a brief note on the "tensions over China" that Gordon mentioned.

Note: It is at this point that one ought to be familiar with just how shrewd Japanese diplomats during the First World War were with their "negotiations" for guarantees in the eventual peace settlement. This previous writeup should be of interest and relevance there.

The Twenty-One Demands

Prior to the Paris Peace Conference, Japan had already sought to capitalise on their success in Asia by pursuing a more aggressive stance in China. In particular, they presented the Twenty-One Demands to the Nationalist government under Yuan Shikai in 1915. These demands would, in essence, make China a Japanese "puppet", if not an outright colony. Anti-Japanese protests in China followed suit, and Anglo-American intervention soon forced the Japanese government under Okuma (who, it should be noted, approved of this maneuver whilst also preaching for racial equality) to remove the last group of demands which were the harshest.

The revised "Thirteen Demands" were finally accepted by Yuan on May 25th, 1915. However, these new demands gave little more than what Japan already had in China, and nationwide anger at the intervention of the West in Sino-Japanese affairs rose steadily.

Part 1 of 2