How can you tell a first printing of One-Punch Man?
The same way you date any Jump Comics volume: the colophon page at the very back.
Japanese manga do not use number lines. A Jump Comics volume carries its printing history on the colophon page at the back of the book, which states the issue date of the printing in hand. A first printing of volume 1 reads as issued on the book’s release date, December 4, 2012; later printings of the same volume carry later dates. That page, not the cover, is the certificate.
THE CHECKS, IN ORDER
Back page first1. Open the back
Turn to the final pages and find the colophon: publisher, title, author credits, and the printing’s issue date. If that date matches the volume’s first release date in this shelf’s gallery, you are holding a first printing.
2. Remember the twin launch
Volumes 1 and 2 share a first-printing date, December 4, 2012, because Shueisha launched the series with both. A volume 2 dated that day is not an error; it is the launch.
3. Know the special dresses
Volume 8 exists in a Seven-Eleven special edition with a changeable cover, and volume 10 in a holiday special edition, also with a changeable cover. These variants sit beside the standard printing, not above it, and are identified by their covers, not the colophon.
4. The redraw caveat
A first printing is the first fixed version of the redrawn text, not the first version ever published: Murata’s online chapters had already been read, and in famous cases replaced, before the book froze one version in ink. Print is the record precisely because the internet kept moving.