We are pleased to announce that the database for Mainichi 毎日新聞 is available to Yale Community.
Maisaku 毎索 (https://dbs.g-search.or.jp/WMAI/WMAI_ipcu_login.html)
The Maisaku database lets you search all the Mainichi Shinbun 毎日新聞 (formally Tokyo Nichi Nichi Shinbun 東京日日新聞, Osaka Nippo 大阪日報, etc) from 1872 (Meiji 5) to present.
Please note that there are two functions, 記事検索 (article search) and 紙面検索 (page search), available. While記事検索 is still not so robust with keyword searching, the search results will be very limited. I suggest you use紙面検索 for full searching.
The database also includes other functions likeヨミロンサーチ which provides newspaper research from October 1945 to June 2011 on public opinions, such as cabinet and political party approval ratings. The data can be searched by keyword and date with sorting functions for categories like gender and age.
Additionally, below is a link to complete list of Japanese Newspapers Yale subscribes.