Books in Japanese University libraries: CiNii Books
Books & digital materials in the National Diet Library: NDL Search
The feed above brings latest e-book acquisitions in Helsinki University Library which have "Japan" as subject term from BookNavigator.
Fields that have their own category in BookNavigator:
Hint: You can also make word searches in BookNavigator like anime, politics Japan and so on.
Main collection for Japanese Studies books is located on the 6th floor (shelves Om 510 - Om 519).
See new books on Japan shelves within 3 months
Shelf Classification for Asian and African Studies
See also Geographical dicrectory Asia (in Finnish)