The Spy: the King of Agents of the Republic of China

It's purely fictional, just enjoy watching it (many fictitious items appear) In the world of spy wars during the Anti-Japanese War of the Republic of China, someone traveled through time and became a lieutenant in the military command, who was also an undercover agent of the Communist Party. He faced pressure from the Japanese army, military commanders, and central commanders, and his mission was full of dangers. Accidentally obtained the "Spy Insight System", which can gain insight into intelligence, redeem skills, and predict situations. This system allowed him to become like a fish in water among various forces, and he quickly stood out, far ahead of his peers. With the help of the system, he rose through the ranks, formed troops, and finally shattered the enemy's conspiracy, became a double-agent king, maintained peace after the war ended, and retired to become a legend.