BWSD-063 - The student who came to care for his teacher and got addicted 3

*Yamada, a former student who is studying to become a caregiver, moves in to care for an older female former teacher. However, it makes no sense to make him spread his legs and urinate on the veranda. There's nothing erotic about it. The first sexual act was pretty normal and not particularly exciting. A female teacher is starved of sex due to loneliness and medical treatment, and entrusts herself to a former student who adores her. I understand, but it's a naive development. I couldn't understand the scene where Yamada's older sister (she's so bad) gets in there and abuses the female teacher and puts her hands on her. After that, what's with the scene where the two show each other masturbation? Furthermore, two thieves break in and rape a female teacher, but was this also necessary?