Aozora Bunko (青空文庫, literally the "Blue Sky Library", also known as
 the "Open Air Library") is a Japanese digital library. This online collection
 encompasses several thousands of works of Japanese-language fiction and
 non-fiction, most of them are public domain books/works, and some are the
 authors wish to make freely available. See https://www.aozora.gr.jp/
 .
 aobook is a viwer for the books/works those are provided by Aozora Bunko.