In this chapter, we trace the historical development of accounting regulation in Japan and construct a historical narrative of the unique coexistence of four sets of accounting standards. Initially, the ASBJ took a cautious approach to the convergence between Japanese GAAP and IFRS. However, the atmosphere changed with the “Tokyo Agreement” in August 2007, and the situation shifted remarkably when the FSA/BAC permitted Japanese companies to voluntarily file consolidated financial statements prepared in agreement with IFRS. After temporarily taking a cautious stance in 2011 and 2012, the FSA and the BAC regained a positive attitude towards IFRS and sought to create examples of voluntary applications of IFRS.