This article explores the notion of the Buddhist canon in seventh- and eighth-century Japan. It relies on scriptorium documents, temple records, and manuscripts of catalogs to argue that there was no single Buddhist canon in ancient Japan; each was created at a particular moment in a unique configuration to respond to the needs of the patron and the monastic community. For this reason, Buddhist canons in the Japanese case are best understood in the plural. But rather than simply focusing on what the canon was as a noun, this article examines the dynamic processes through which canons were produced as systematized collections of texts. It shows how monks, rulers, and administrators in the capital consulted continental catalogs but were never bound by them. Canon copying provided a means for individuals at court to demonstrate their mastery over the Buddhist tradition.