Kamada Takuma

Main Research Areas

My research seeks to understand the causes and consequences of crime and its enforcement. I am particularly interested in two main areas: (i) the effects of public policies (both criminal justice policies and socioeconomic policies) on criminal behavior, and (ii) the effects of drug epidemics on neighborhoods and cities. For more details, please refer to my personal website: https://tkmkmd.github.io/

Research Overview

I’ll briefly introduce some recent research on each of these threads.

Research Thread 1: The liberalization of crude oil imports and the change in coal policy in Japan during the 1960s led to an energy transition, shifting the primary energy source from coal to oil. During the coal era, some yakuza groups were involved in the coal mining industry as labor brokers and protection racketeers. This study examines both the short- and long-term effects of the energy transition on yakuza activities. The figure below shows that areas that experienced a more historical decline in coal mine workers due to oil imports have seen increased contemporary yakuza activities.

Research Thread 2: In the United States, drug abuse involving prescription painkillers, opioids, has been a serious public health issue since the late 1990s. In the early phase, the White population was disproportionately affected, due to racial disparities in health insurance coverage. This study examines the effects of an abuse-deterrent opioid policy, aimed to curbing the abuse of prescription opioids, on neighborhood change. The figure below shows that the policy change leads to the emergence of White high-poverty neighborhoods.