There's someone who's constantly glaring at my girlfriend's older sister—and that someone is Konatsu, a little sister with a serious brother complex who adores her big sister. Konatsu deeply cherishes her sister and is extremely unhappy about my presence. She snaps at me, saying, "Why are you here again? Just go home!" The one who gently calms her down is her sister, Mei. Mei is incredibly kind, an angelic girl who always maintains a gentle and serene demeanor. However, she seems bothered by our affectionate moments and starts interfering. Then she honestly confesses, "Onee-chan, I know you love Konatsu, but I love you too." Mei softly replies, "Don't make such a sad face, Onee-chan…" But Konatsu, surprisingly not angry this time, suggests, "Then… let's have sex together, the three of us?" Until now, Konatsu had only shown an angry expression, but it turns out she actually has a cute, adorable face—especially with her loli twin-tails, making her incredibly attractive. Meanwhile, Mei notices, "You seem more turned on than usual… it's making me jealous." Yet, faced with these two girls, I can no longer hold back. How could I not be excited, surrounded by such stunning big-titted sisters?