 Rosen’s most important scholarly writings are devoted to introducing the strange and mysterious phenomena witnessed in his castle town and neighboring villages and landscape. His New Treatise on the Spirit Realm (Yūfu shinron) completed in 1865 cites the teachings of Atsutane on the invisible kakuriyo spirit realm and utilizes these to explain previously inexplicable events in his community. Rosen asserts such objectives of his most seminal work: 