I'm an older sister who decided to verify why my younger sister, who always says things are unfair, constantly complains about unfairness. And I also can't understand why she took away my fiancé and broke off my engagement... This is my complaint as I struggle, unable to solve this mystery no matter what.

"She's always unfair, unfair," my younger sister complains, saying I'm the unfair one. I observed why she desired my possessions. I realized it was because I'm the heir apparent that made her angry, and even when a younger brother was born, I thought this jealousy would disappear, but it remained unchanged. And because my fiancé is the crown prince, she kept saying "unfair, unfair," and even stole my fiancé away from me... I cannot understand that child, but I have observed her long enough that I can roughly predict what will happen next. Let me observe as I always do.