Board Thread:General Discussion/@comment-32144419-20171209173120

In season one of the anime, Kaneki visits a cafe with Shuu Tsukiyama, his finger is cut on the shina cup that Tsukiyama breaks.. In volume 4 chapter 36 its a paper cut on a book. But how does Kaneki recieve this injury if normal blades cant peirce ghouls skin? 