Okay I know we're all joking about how it makes sense that they're family with how scummy they are. But I wonder how much of Itsumi's actions are from her sisters isolation driving her to being desperate. Her sister even said it herself, Itsumi was about to be driven to the deepend.
Itsumi isn't really good at anything and she's kinda dumb, but I think being a scumbag comes from being desperate for someone's attention. Even going so far to drugging her teacher to have someone. She only wants positive attention because she's only ever received negative harsh reactions from everyone around her. That's why she's calmed down since bonding with the other girls. She's gone from a scumbag to a pevert now tbh.
In conclusion, I'm a Itsumi apologist. Rin best girl
