My poor younger sister was cheated on by her older sister.
It's really sad for the lovely and adorable girl to discover that her "bear" is secretly fooling around with her older sister.
With a perfect figure: firm bust, slim waist, ample hips, and ideal height, the younger sister is completely overshadowed by her beloved older sister, which is why her boyfriend also changes his heart, secretly developing feelings for his future sister-in-law...