Power transition theory (PTT) has effectively explained the concept of war among great-power states and has successfully competed with the balance of power theory since Organski proposed it in 1958. PTT’s main argument is as follows: when one state’s power approaches that of another state and it is dissatisfied, it is highly likely that the state will initiate war. Lemke (2002) further applies PTT to regional wars and argues that PTT is powerful in explaining both hegemonic wars and regional wars. This paper follows Lemke’s definition of regional dyads and focuses on Northeast Asia. However, both the statistical and qualitative analyses in this paper reveal results that are distinctly different from PTT’s arguments, in particular on the dyad of China and Japan. To be specific, this paper examines the power ratio and state dissatisfaction of Northeast Asian dyads from 1918-2007 and further induces the conflict behavior of Japan and China by means of Boolean algebra. The results show that the shrinking power gap is not as influential on China’s and Japan’s behavior as PTT argues. Instead, China will initiate war when it has greater power than another state. China will also initiate war when it is highly dissatisfied. As for Japan, although dissatisfaction will lead it to war, the superiority of its military and economic power has more of an influence on its conflictual behavior. A case study on the first Sino-Japanese war in 1894 concurs with the arguments of this paper. Finally, the results of this paper also correspond with the story that China still follows the principle of “tao guang yang hui” proposed by Deng Xiao-ping.