This is a huge bookstore (located in the Annex) which sells used books and remainder copies of new books (you can tell by the marker spot on the edge of the pages).
If you are looking for a particular book that is out of print, be sure to check this store because there is a big chance that a copy will circulate through here.
This bookstore offers many books, plus cd's, comics, and even movies. You can still find old VHS tapes here!
On the third floor, they offer comics and manga.
This bookstore offers books at lower prices compared to other used bookstores.
BTW, if you purchase a lot of books, you can pay by debit.