In August 1994, Prime Minister Tomiichi Murayama promised at home and abroad to establish a "Center for Asian Historical Records" that would "collect history books and materials, support researchers, etc., for squarely facing past history" as the centerpiece of the "Plan for peace and friendship exchanges," to commence the following year in commemoration of fifty years from the end of World War II. A committee of 15 persons of learning and experience was placed in charge of drafting concrete plans for the Center. This committee took into consideration fact-finding studies performed both in and out of Japan, opinions of informed persons, and more broadly the requests from the general public, and in June 1995 recommended that the Center be established "for impartially collecting a wide variety of materials and information on modern history of Japan and neighboring Asian countries and other countries, and helping researchers as well as the general public at home and abroad hve easy access to them." Based on this thoroughly considered recommendation, the Government entered into concrete study for establishing the Center and on November 30, 1999, as part of the "Project for comprehensive collecting of Asian historical records, " the Cabinet decided upon providing access through the Internet to "Asian historical records," which various ministries and agencies of Japan have been preserving and making available to the public. After 2 years of preparation, JACAR was opened on November 30, 2001, as an institution of the National Archives of Japan.

A lot of precious modern historical records have been lost or become scattered in Japan due to natural disasters such as earthquakes and typhoons, fires resulting from air raids, burning and destruction of important documents during the chaos of wartime, and other factors. Among records preserved, those of the Showa period produced with inferior quality paper are also rapidly deteriorating. On the other hand, a series of studies has found large quantities of precious historical records still preserved by Government institutions. It was also learned that a lot of these materials were being made available to the public by institutions specializing in the preservation of such materials. The circumstances surrounding these institutions for the preservation of materials however have much to be desired for compared to their counterparts in various foreign countries. Facilities to preserve and peruse historical records and archivists receive little social recognition, in fact. This situation has stifled the efforts by collection institutions to maintain catalogs of details indispensable for searching materials and development of finding aids. Only a portion of experienced researchers has been capable of using the materials consequently.

The Japan Center for Asian Historical Records （JACAR） addresses this disadvantageous situation of our country's modern historical records by utilization of the most advanced technology with the aim of providing anyone the means to peruse, print, and download image-data of records at anytime, from anywhere, at no charge. In accordance with the decision by the Japanese Cabinet, the Center is first digitalizing and providing access through the Internet to Asia-related records dating from the early Meiji era to the end of the Pacific War in the possession of important collecting institutions of pre-war official documents, The National Archives of Japan, Diplomatic Archives of the Ministry of Foreign Affairs of Japan, and National Institute for Defense Studies of the Ministry of Defense. The number of image data produced from the materials these institutions possess alone is estimated to exceed 28,000,000. As of April 2011, users now have ready access to 22,460,000 pieces of image data and a catalog database of 1,620,000 items, which will be augmented on an ongoing basis.

The Center can be considered a full-fledged digital archive of digitalized images of historical records and database of cataloged information accessible through the Internet. Image data becomes online information upon processing by the DjVu, the most advanced image compression technology developed for making large quantities of text contents accessible through the Internet. The catalog consists of approximately the first 300 characters of each document, thus not only the title but also a portion of the text becoming subject of search.

Users have ready access to our information using browsers running on either Japanese or English operating systems. For simple explanations for the searching systems in each of the languages, refer to their respective pages.

Merits of the Japanese-language search system

This system furnishes such functions as "layer search" for searching through layers according to the classification structures of each collection institution, "keyword search" for searching with a keyword across all collection institution materials, "detailed keyword search" for flexibly searching with synonyms and related words that can be multiply selected and applied with "and" and "or" conditions, as well as "reference code search" to search directly for material according to the individual code number assigned to each catalog item. The functions of synonyms and related words serve the purpose during searches of electronically linking currently used historical terms such as "Pacific War" and "Sino-Japanese War" with "Greater East Asia War" and "China Incident," and such terms actually appearing in the documents that were in use at that time.

Merits of the English-language search system

As the title of catalog items are translated into English, English keywords can be used for searching through the titles in English. English translations of basic historical terms such as "Pacific War" and "Sino-Japanese War" have been registered as synonyms and related words to their counterpart terms in Japanese, and thus catalog items in Japanese can be found through search by English words as well by activating the synonym and related-word functions. English translations of historical terms were determined after examination of terms appearing in the indices of English-language books concerning modern Japanese history, such as the Cambridge Modern History, Japan and China. In cases of terms that have no common English translation, we have romanized the Japanese term. Foreign-language proper names were spelled with the confirmed spelling in the original language as much as possible, but in cases that confirmation was not possible, we applied romanized notation or common English spelling for the term. For names of persons, places, institutions, and other matters relating to China, we applied the Pinyin system as a general rule, and provided the Wade-Giles system of spelling alongside in case the latter system is used commonly for the particular term. In cases of Japanese katakana syllabic notation with no means of confirming the original terms in Chinese, we applied romanized notation. Romanized notation, however, have been applied as an expedient measure and not comprehensively for all terms. It is advised therefore that the user conducts searches with a combination of Pinyin, Wade-Giles systems, and romanized notation as needed.