Martial Artworks was a catalog in Club Penguin, located in the Dojo, and before its removal, the Ninja Hideout. Only members could buy items from this catalog. Every page used to have a small story written in haiku which related to the item on the page, but this was removed when the catalog was redesigned in May 2013.
Despite all other catalogs having a popup labeled "You found a secret!" when a secret item was clicked, the Martial Artworks catalog instead used the old secret item popup, simply showing the item or items on a slip of paper.