The bill to amend the Japanese Antimonopoly Act (AMA) finally passed the Diet on 19 March 2019. The amendments will increase the amount of the administrative fine, called a surcharge. This low surcharge is routinely criticised. Despite several changes made to the current system, the surcharge is likely to remain low in comparison with similar international levies, which could indicate a lack of political will to combat cartels in Japan. This article challenges this view and argues that the long-standing rationale behind the surcharge system—disgorgement—is reflected in the surcharge level. We argue that the distinguishing features of the Japanese fining system are this fidelity to disgorgement rather than deterrence, and the coexistence of the administrative surcharge and the criminal fine, both of which the government can impose on the same company for the same activity. We are sceptical of deterrence theory, which underpins the enforcement approach of many leading competition law jurisdictions elsewhere, and contend that the Japanese approach could help keep its fining system legitimate and effective. After emphasising the importance of legitimacy of cartel fining system, the article explores overlooked aspects of the Japanese fining system. It then points out that further reforms are still necessary, particularly as a significant challenge looms: how Japan will be able to keep its dual system given that deterrence theory is the global norm.