I think grandpa used to hit Kazumi with harisen made from newspaper paper (you can see Reitaro holding one in the final panel). Also explains the Kazumi’s beatings being “so strong they echoed through the whole house” thing cuz harisens are loud.
However, being hit by a harisen shouldn’t be...
“Disgusting humans” the murdering slaver with rapist subordinates thinks to himself after the dirtbag husband whom he made a deal with has the audacity to ask him to honor said deal.
Could our dear murdering slaver be a hypocrite, perchance? Of course not! The murdering and the slaving is...