Actually chances are people quite literally crapped on the guy below hence why he might've wanted paper, that or he needed to wipe after falling through the seat, cuz let's be honest it's two pieces of wood not nailed down.
Because the toilet represents the humanity that's left in the world. To show that even though the have magic and all that, they're still human. Plus the toilet wants to be there so leave the toilet be lol
Just keep away from my sexbot! She never harmed anyone!! D: unless I have her set to dominatrix...
*ahem*
... because in a series out of Japan known for its random weirdness in a game that is twice and again as utterly batsh*te BONKERS as all the others ...
of course there's gonna be a hand reaching out of a conspicuously placed toilet begging for paper.