This scene is all about cold cold metal and the unforgiveness of such metal and Hinako. First, putting her sub in a small cage and attaching handcuffs to his wrists, the situation is already dire enough, but is made even worse by the addition of a myriad of chains wrapped around his body, all the way up to his face. Hinako locks the cage and sets down the key, telling him he can use this to leave whenever he wishes, but the chances of him being able to reach that key are quite slim.