Here is a short list of newspaper article databases and print reproductions of Japanese newspapers:
Asahi Kikuzo II Visual: Full text access to 朝日新聞 (1879-present) and Historical Photo Archive, containing ca. 10,000 pieces of historical photographs taken in Asia and Europe from the 1930s to 1945
Factiva: Provides access, mostly to full text, to nearly nine thousand business and general news sources, including U.S. and international newspapers, magazines, and wire services; includes major Japanese newspapers such as 読売新聞, 毎日新聞, and 産経新聞 (warning: covers only recent years)
Nikkei Telecom 21: Full text access to 日本経済新聞 (1876/12/2-1961/12/31, and 1981/10-present), 日経産業新聞 (1981/10-present), 日経流通新聞 (1985/10-present), and 日経金融新聞 (1987/10-2008/1) is provided; it also offers English sources such as Nikkei English News, Nikkei Weekly and translations of major articles from the above-mentioned Japanese newspapers, as well as Nikkei Company Profile (30,000 company profiles) and Nikkei Who's Who (20,000 corporate executive profiles).
Shinbun shūsei Meiji hennenshi 新聞集成明治編年史 / [編纂代表 中山泰昌]: Selected articles from numeous Japanese newspapers in the Meiji period in chronological order.
Shinbun shūsei Shōwa hennenshi 新聞集成昭和編年史: Selected articles from numeous Japanese newspapers in the Showa period in chronological order.
Shinbun shūsei Taishō hennenshi 新聞集成大正編年史 / 明治大正昭和新聞研究会編: Selected articles from numeous Japanese newspapers in the Taisho period in chronological order.
Yomidasu Rekishikan ヨミダス歴史館: Full text access to Yomiuri shibun 読売新聞 (1874-present) and Daily Yomiuri (1989-present). The database also provides dictionaries (Japanese/English, English/Japanese, or new words dictionaries) to look up definitions and biographies, just by highlighting any words in the article and clicking dictionary buttons