The samurai were primarily Japanese. They were a warrior class that emerged in Japan during the late 12th century and became prominent in the feudal period. Their origins can be traced back to the Heian period when local nobles employed armed retainers for protection and military service.
In contrast, China had its own distinct warrior classes and military traditions, such as the scholar-officials and various dynastic armies, but these groups were not the same as the samurai. The samurai developed a unique culture, code of conduct known as bushido, and a distinct social status that was tied to Japanese history, politics, and society.
While there were interactions between China and Japan, particularly during periods of trade and cultural exchange, the samurai as a concept and social class is uniquely Japanese. Thus, the answer to the question is clear: samurai were Japanese, not Chinese.