Despite being one of the most avowedly secular nations in the world, Japan may have more prison chaplains per inmate than any other country, the majority of whom are Buddhist priests. In this groundbreaking study of prison religion in East Asia, Adam Lyons introduces a form of chaplaincy rooted in the Buddhist concept of doctrinal admonition rather than Euro-American notions of spiritual care. Based on archival research, fieldwork inside prisons, and interviews with chaplains, Karma and Punishment reveals another dimension of Buddhist modernism that developed as Japan’s religious organizations carved out a niche as defenders of society by fighting crime. Between 1868 and 2020, generations of clergy have been appointed to bring religious instruction to bear on a range of offenders, from illegal Christian heretics to Marxist political dissidents, war criminals, and death row inmates. The case of the prison chaplaincy shows that despite constitutional commitments to freedom of religion and separation of religion from state, statism remains an enduring feature of mainstream Japanese religious life in the contemporary era.