The physical characteristics of paper books are closely related to human cognition, and this is the reason why books have gained a privileged position in academia, literature, and education in the modern era. However, in media studies, following McLuhan’s work, multimedia has been considered more influential due to its sensory attributes compared to the medium of books. In the 21st-century Internet society, all forms of media, including books, have become absorbed into the digital network. In this paper, we have divided the media into two categories: containers, which are the mechanisms for carrying messages, and contents, which are the messages themselves, and have historically examined the transition of media. We then discuss the need to take advantage of the historical characteristics of books in distribution, retrieval, and archiving, and the role of the Digital Collection of the National Diet Library as a model in this regard.

Based on an Amendment to Copyright Law in 2021, the destination of National Diet Library’s Digitized Contents Transmission Service for contents of out-of-print materials will be expanded from partner libraries to individual users in 2022. This article summarizes the current status of digitization of materials by the National Diet Library and the Digitized Contents Transmission Service for partner libraries, and then introduces the background of this amendment, as well as Transmission Service for individuals in preparation.