So, she doesn't mind being his fap material or drinking his cum
She goes on trips with little luggage
She's trying to make him get horny and cum to other girls
She's used an onahole on her brother while making him believe they were having sex (and she tricked him using another onahole, probably one she had)
She won't allow her friend Haruka to be fap material, but she will allow her other friend Yuka to be
Seems like Yuka doesn't mind her taking lewd pics of herself
She won't forgive him if he looks inside her wardrobe
Honestly, I couldn't care less about the protagonist, I just want to know what his sister's secrets are.