Final answer:
Japan was bitter towards Western countries post-WW1 because of inadequate recognition at the Treaty of Versailles, Western racism exemplified by U.S. immigration policies, and Western opposition to Japanese expansionism and leadership in Asia.
Step-by-step explanation:
Japan felt bitter towards Western countries after World War I for several reasons. First, despite Japan being part of the victorious Allied coalition, their significant contribution was not adequately acknowledged at international negotiations like the Treaty of Versailles. Japan's proposed racial equality amendment was rejected, fueled by Western powers' insistence, which was a clear demonstration of Western racism against Japan.
Secondly, Japan was also subject to Western racism through policies such as the United States' prohibition of Japanese immigration. This legislative discrimination amplified the perception that Japan was not regarded as an equal by the West. The deep-rooted sentiment of racism towards Asians, dating back to the 19th century, played a significant role in the nation's grievances.