Traveling Through the World Tree in the Siheyuan

Lin Feng, a deliveryman in the 21st century, travels through 1945 in Peiping and uses modern knowledge + plane resources to gain a foothold in troubled times. He slaps the best neighbors in the courtyard, accumulates wealth and strength, "picks up leaks" in different planes (such as bringing back urgently needed medicines for the Anti-Japanese War, future technical materials, and basic exercises in the world of immortality), protects the people around him and affects the times.