The architecture of writing systems metaphor has special relevance for understanding the structural nature of the Japanese writing system, and, more specifically, for appreciating how the 2,136 kanji of the 常用漢字表 /jō-yō-kan-ji-hyō/* ‘List of characters for general use’ function as the core building blocks in the orthographic representation of a considerable proportion of the Japanese lexicon. In seeking to illuminate the multiple layers of internal structure within Japanese kanji, the Japanese lexicon, and the Japanese writing system, the paper draws on insights and observations gained from an ongoing project to construct a large-scale Japanese lexical database system. Reflecting structural distinctions within the database, the paper consists of three main sections addressing the different structural levels of kanji components, jōyō kanji, and the lexicon. Keywords: Japanese writing system; building blocks; jōyō kanji; components; orthographic structure; database