How do we explain the seeming instability of contemporary relations between Japan and the People's Republic of China? As both the world's second and third largest economies and neighboring naval powers with expanding capabilities, the relationship between Japan and China arguably now ranks as one of the most internationally significant. In the realms of security, economics, environmental protection and more there exist strong reasons for mutual cooperation. And yet the relationship has been subject to repeated episodes of mistrust, tension, and mutual recrimination despite periodic elite attempts to foster better relations. In explaining this pattern, existing analyses have tended to invoke a mix of three factors: security issues, economic ties, and emotions. But while analysts have availed themselves of the ample theoretical tools the field of international relations supplies for addressing security and economic relations, references to emotions have generally been quite ad hoc. Indeed, the adjective "emotional" can and has been used to describe everything from nationalist outbursts in online forums, broad sentiments reflected in polls, the sensitivity of certain issues, to even the personal attitudes of policymakers. In analyses of the relationship, emotion has often played the role of a dark matter whose influence is ubiquitous but whose exact properties and variant forms remain a mystery. The goal of this project is to illuminate the role emotional and affective factors may have played in generating the pattern of volatility observable in recent Sino-Japanese relations. Building on my previous work, this project will disaggregate the different phenomena lumped under the term "emotional" to theorize how they may interact not only with one another but also the complex socio-political context of Sino-Japanese relations, paying particular focus to the incentives various actors on both sides face to engage in emotional politics (that is, frame issues in ways that evoke emotion) and politicize emotion (i.e. treat the feelings of certain actors or groups as requiring political deference or defense). By developing clear expectations of when and how particular emotions and affective phenomena—whether in the form of popular indignation or more subtle forms of affinity or animosity—may influence relations between the two countries it becomes possible to pursue a systematic empirical appraisal of their effects. Specifically, conducting research in both Tokyo and Beijing, drawing upon Japanese and Chinese language source material and interviews, this project will reconstruct the events of the last fifteen years to assess the extent to which an approach that additionally incorporates emotion and affective phenomena can explain oscillations in the relationship existing theories cannot. In doing so, this project will not only add to our knowledge of Sino-Japanese relations since the turn of the century, it will also aim to replace folk theories and implicit assumptions with a theoretically rigorous and empirically grounded account. Consequently, this project holds the potential to better inform policy debates and inspire new policy recommendations, especially when it comes to changing the incentives driving particular forms of destabilizing emotional politics and cutting short cycles of mutually damaging escalation.