My girlfriend was away and secretly fucked her premature ejaculation sister who seemed weak to pushing her, 7 days of living together

Exclusive 4th edition! First time trying out Yagi Nana drama! My house had both the lights and gas stopped, so I ended up staying at her house for a while. She has a younger sister, and it's the first time I've seen her... she appears to be on my guard, showing her face from her back. "Nice to meet you, this is Nana," her younger sister said in a slim voice, shy and shy voice, and apparently she's an innocent girl who has no immunity to men. She's so weak to pushing that she can have sex right away, and she's a sensitive, trembling premature ejaculation girl! A week of having sex with my younger sister without telling her!