The University Libraries use a system called the Library of Congress Classification. Items in the library received their call number based on this system, which groups books about similar topics together. They are essentially addresses for materials on shelves, with no two items having the same address.
If you are doing research on anime or manga, you may come across the book マンガ・アニメにみる日本文化. In the record you will notice a feature "Search Nearby Call Numbers" which will show a great deal more books dealing with the topic. It's like looking at a virtual shelf of books. You can also associate the call number PN6790.J3 with scholarly discourse on anime and manga. Apply this to any topic you are interested in.
You'll become familiar with call numbers that correspond with your research interests. You can take the call number in the example above and search some the largest Japanese Collections in country: