This might be against the global trend of ‘saving resources' and 'reduction of rubbish' but if you buy a book from Japanese bookshops, they usually put a cover on the book by folding the wrapping paper with the bookshop logo very quickly.
Why is the cover supported?
One of the two major reasons is because it covers the reader's privacy － many people don't want others to know where their interest lies being learnt from what they are reading.
The other reason is that they want to preserve the books as neat and clean as new.
There are more practical reasons for the book shops
If the book is covered with their wrapping paper, it is obvious that the book has been paid at the cashier.
Besides the logo on the paper is an inexpensive but highly efficient mode of advertisement.
Actually, bookshops have been trying to be creative in the design of the wrapping paper as people would not be happy to carry something embarrassing.
You have a choice whether you like your book covered or not as the shop clerk asks you.
Some people refuse to have it thinking it's not necessary so prefer to save papers, while some others refuse because they have their own book cover already which are usually made of leather or fabric for long term use.
Japan has a tradition to consider that covering item is a courtesy
Especially when they are giving something to someone, even a small and simple item, giving it unwrapped is considered rude.
Therefore, wrapping service is available at almost every kind of shops and stores ‘upon request' and usually it's free of charge unless you have any special request like boxing.