During the early Hean period in Japan, between Saicho (最澄 767-822), who belonged to Tendai School, and Dokuitsu (德一 760年?-835年?), who belonged to Hoso school, a series of controversies were unfolded, which are considered as the first debate in the history of Buddhism in Japan. The Controversies can be summarized in two major aspects. The first aspect is related to the truth whether Sakyamuni’s doctrine was Ekayāna (一乘 ‘one vehicle’) or Triyāna (三乘 ‘three vehicle’)? In this article, I focused on the issue of “non-buddha-nature beings” (無性有情), which will be discussed through whether vegetation (草木) bears Buddha-nature or not. The second aspect is related to the teaching of Tiantai School. I emphasized the controversy of śamatha- vipaśyanā (止觀, ‘meditation’). Specifically, Dokuitsu criticized the statement of Yen Dun Zi Guang (圓頓止觀) proposed by Zi Yi (智顗, 538-597年), who was the founder of Tiantai school in China. In Taiwan, the study of Japanese Buddhism was rarely explored; even Buddhist scholars know little about this controversy. But the controversy is concerned with the development and change of Buddhism from China to Japan. Thus, from a Chinese Buddhist’s viewpoint, I attempt to re-examine this controversy in order to further reflect the sense of this issue today.