Designing a database for categories and subcategories - database

Question

Basically I'm trying to figure out how Amazon architected their book section. Check out Amazon's book page here (https://www.amazon.com/s/ref=lp_2_ex_n_1?rh=n%3A283155&bbn=283155&ie=UTF8&qid=1522817105).
We are given several main categories: Arts & Photography, Biographies & Memoirs, etc.
If I click on Biographies & Memoirs for example, I'm lead to a series of sub categories. I.E. Biographies & Memoirs > Historical > Asia > Japan
There are repeating sub-category names for example: History > Asia > Japan
How can I map this kind of information so that it is scalable?
Below is the wrong way to do it...?
Categories table
+----+-----------------------+-----------+
| id | name | parent_id |
+----+-----------------------+-----------+
| 1 | Biographies & Memoirs | null |
| 2 | Historical | 1 |
| 3 | Asia | 2 |
| 4 | History | null |
| 5 | Asia | 4 |
| 6 | Japan | 5 |
| 7 | Japan | 3 |
+----+-----------------------+-----------+
Books
+----+-------------------------------------+----------+
| id | name | category |
+----+-------------------------------------+----------+
| 1 | The Lone Samurai | 7 |
| 2 | The Human Tradition in Modern Japan | 7 |
| 3 | Okinawa: The Last Battle | 6 |
+----+-------------------------------------+----------+
Authors
+----+---------------+----------+
| id | firstname | lastname |
+----+---------------+----------+
| 1 | James M. | Burns |
| 2 | Roy E. | Appleman |
| 3 | Russell A. | Gugeler |
| 4 | John | Stevens |
| 5 | William Scott | Wilson |
| 6 | Anne | Walthall |
+----+---------------+----------+
Authors to books (Many to many)
+---------+-----------+
| book_id | author_id |
+---------+-----------+
| 3 | 1 |
| 3 | 2 |
| 3 | 3 |
| 3 | 4 |
| 1 | 5 |
| 2 | 6 |
+---------+-----------+