義妹は普段から口数が少なく正直何を考えているか全く読めないいわゆる陰キャ女子。ただなんかエロい雰囲気なので正直エロい目で日々彼女のことを見ていた。するとある日『そんなに私とエッチしたいんですか？』『別にいいですけど』『ゴムは着けて下さいね』『私はスマホ見てるので挿れたかったら勝手に挿れて下さい』と事務的にセックスOKのお誘い。挿れさせてくれるなら、この程度の条件いくらでも飲みます！そして待望の挿入…やっぱりスマホ鑑賞するんだ…。しかも反応が薄い…。というか全く反応なし！でも、こっそりゴムを外して生ハメすると…なんと無反応だった義妹が喘ぎまくってエビ反りでイキまくり！とんでもないそのギャップにボクはさらに興奮して激しくなる腰の動き！そして何度も何度もイキ狂う義妹。クールぶってるけど中身は超淫乱女子でした。

My sister-in-law is usually a quiet girl, and honestly, it's impossible to tell what she's thinking. She's what you'd call an introverted girl. But she has a sexy aura about her, so I honestly looked at her with lustful eyes every day. Then one day she asked me, "Do you want to have sex with me that much?" "I don't mind," "Please wear a condom," "I'm looking at my phone, so if you want to put it in, go ahead and do it," giving me a businesslike invitation to have sex. If she's going to let me put it in, I'll accept any conditions like that! And then came the long-awaited insertion… and of course, she was looking at her phone… What's more, her reaction was minimal… In fact, she didn't react at all! But when I secretly took off the condom and went in raw… my sister-in-law, who had been unresponsive until then, started moaning like crazy and arching her back as she came! The huge contrast excited me even more, and my hips started moving more violently! And my sister-in-law came again and again. She acts cool, but inside she's a super slutty girl.