How Can You Tell If a Japanese Naruto Volume Is a First Printing?
Japanese collected volumes print their own biography on the final pages. The colophon, called the okuzuke, lists the publisher, the release date and the printing history of that exact copy. For a first printing of Naruto volume 1, the colophon shows the original March 3, 2000 date with the first printing notation (the characters for first edition, first printing) and nothing after it. A later printing adds its own line and date, second printing, third printing and so on, in order.
This is why serious listings for Japanese manga photograph the colophon. The covers of a first printing and a fifth printing of the same Naruto volume are identical, the paper feels the same in a photo, and the ISBN matches, because an ISBN identifies the edition, not the printing. The colophon is the one page that separates them, and any seller who will not show it is asking the buyer to guess.
The obi, the paper advertising band wrapped around the bottom of a new copy, matters too, but differently. Obi were thrown away by most original buyers, so a surviving first printing with its original obi is a more complete object. But an obi is loose packaging: it can be lost from a genuine first printing and, less honestly, swapped onto a later one. Treat the obi as a completeness bonus on top of a colophon that already checks out.
The English equivalent
Viz's English Naruto volumes use the Western system instead: a number line on the copyright page. A first printing shows the full line running down to 1. There is no obi tradition on the English books, so the number line and the printing date carry the whole evidentiary load. The Library records Japanese and English first printings separately, since they are different objects with different print histories.
Search terms that find them
Japanese sellers label first printings with the word shohan (first edition) and advertise the colophon wording dai-issatsu (first printing). A copy with its band is obi-tsuki, and a full 72 volume set in which every volume is a first printing is listed as zenkan shohan, all volumes first edition. Knowing the vocabulary is most of the skill: the books themselves then only need the colophon photo to confirm what the title claims.