It's really hard to say. The great cultural exchange between China and Japan was in the Tang and Song Dynasties, and the most famous Japanese Dao was modified according to China and tangdao. Japanese ceramics industry was also taught by China people. Even Japanese characters were handed down from the Sui Dynasty. During the Tang and Song Dynasties, China told the Japanese how to build a house, how to farm, how to farm and weave, how to make laws and so on. China has taught Japan a lot in history and is the second parent of the Japanese.
As for theft, it was rare in ancient history, because it was actively taught. In modern history, Japanese technology is mostly superior to China, so there is nothing to steal.