My cute, kind and proud sister was a lewd, masochistic!

She is a sturdy and beautiful older sister who works on behalf of her parents and also handles housework. One day, when I got home, I saw my sister indulging in absolute obedience sex, calling the man in the neighborhood "master" and pleading with, "Please... Please let me lick your dick." When I see my sister's lewd appearance, she gets an erection regardless of her will. During sex with an old man, I met my sister's eyes, and then I questioned her...