China is upset with Japan primarily due to longstanding historical and geopolitical issues. Key points of tension include territorial disputes over the Senkaku Islands (called Diaoyu Islands by China) in the East China Sea, differing views on Taiwan (which China considers part of its territory), and controversies surrounding Japan's wartime history, particularly Japan's perceived lack of full responsibility for war crimes and visits to the Yasukuni Shrine, which honors some WWII Japanese war criminals. China's military activities near the disputed islands and the increasing defense postures of both nations add to the tensions. Additionally, Japan's defense policies and alliances, especially with the United States, are seen by China as destabilizing and a threat to regional security. Despite strong economic ties, these geopolitical and historical disputes continue to strain China- Japan relations in 2025.