Sometimes wandering the shelves is useful. If you can find one book on a topic, others like it will be sitting on the same shelf. Be sure to look in both the Reference collection on the first floor for general helps like encyclopedias, and in the circulating collection on the second floor for books you can take with you. These numbers work for most other academic libraries as well.
PL501-889 Japanese language and literature
PL501-699 Japanese language
PL700-889 Japanese literature
PL700-751.5 History and criticism
PL784-867 Individual authors and works
PL 885-889 Local literature
For more in-depth information, see Library of Congress Classification Outline: Class P