What is isbn?
An ISBN is the 13-digit identity of a specific book, printed as a barcode. Hondana uses it to find an edition and a volume without asking a model to guess.
ISBN-13 numbers used on books start with 978 or 979. Older books carry a 10-digit ISBN; Hondana accepts that and normalizes it. The check digit has to be valid. A mistyped number is rejected rather than matched to a neighbour.
When the ISBN is already in the catalog, adding the book does not call an AI model. The lookup is a database read: series, edition, volume range, printing. That is the “scan once, right forever” path, and it is free with no monthly cap.
Imports, doujinshi, and old printings sometimes have no barcode you can use. Those go through a cover photo or a form. The photo proposes a match. You confirm it. The catalog gains an entry only after that confirmation, and the photo itself is not kept, only a fingerprint used to avoid repeat work.
Related
See the words on a real set in the edition catalog.