Some official goods have been released during Comiket.
Birz Bookmarks - A set of four bookmarks released by Hisago for the event. When people brought in the barcode from a certain volume of Comic Birz, then purchased any item from the Collaboration Series while there, they had their choice of a free bookmark.
The bookmarks feature the same art as the eco bags and copy memos. The available characters were Prussia, England, Japan and Spain.