BF-519 Complete POV. My Sister In Law Is Yui Hatano

I came to visit my brother and his wife in Tokyo from the countryside during the summer vacation. Yui’s sister-in-law, who she met for the first time in a long time, is bright and kind, and beautiful enough to be a waste for her older brother. But my big brother suddenly went on a business trip and ended up alone with Yui’s sister-in-law…