The development of digital methods to transcribe a large volume of historical documents are the subject of active research in the field of digital humanities. This paper reviews the state-of-the-art technologies and projects focused on large-scale transcription of Japanese historical documents. It is estimated that of the 20 billion plus pre-modern documents preserved across the country, only a handful have been transcribed despite the long efforts of historians. For effective information retrieval from these documents, information scientists and digital humanities scholars in Japan have made various attempts, with methods grouped into two categories: (1) a crowdsourcing approach represented by projects such as Minnade Honkoku, Wikisource, Aozora Bunko, and Hondigi and (2) machine recognition approaches such as MOJIZO, DSC Search, and Kuzushiji Challenge. After a brief description on the bibliographic nature and writing system of Japanese pre-modern documents, the author will examine these projects and their technical backgrounds.