* Waterstones is a popular bookstore chain with a large selection of manga. You can find the Norwich store at 11-13 London St, Norwich NR2 1AL.
* Forbidden Planet is a comic book and science fiction store that also has a good selection of manga. You can find the Norwich store at 4 Castle Meadow, Norwich NR1 3DE.
* Game is a video game store that also has a small selection of manga. You can find the Norwich store at St Stephens St, Norwich NR1 3SP.
* Secondhand bookstores often have a small selection of used manga books. You can find a few secondhand bookstores in Norwich, including The Book Shop (15 Elm Hill), Jarrolds (London Street), and Oxfam Books (20 Pottergate).
You can also buy manga books online from a variety of retailers, such as Amazon, Book Depository, and RightStufAnime.