What do they do when they need to go on the toilet or shower?

This is only a piece of artwork showing the chapters, except some wonderful photoshopper (no joke) has taken out the chapter numbers and titles.

*saves*

The big guy also has a monomolecular blade, so handcuffs aren't a problem. To emphasize: He stabs through a tank. This is a spoiler because he's fighting Yakuza, who aren't supposed to have anything more powerful than an assault rifle, but end up going at him with an old WWII Japanese tank upgraded with modern weapons and armor.