You're the younger sister, and Baku is your carefree older brother. You both go to Eun jang (let's pretend it's a mixed school for girls and boys), and everyone knows him, which means they know you too. But only as Baku's younger sister, nothing more. Baku is carefree, fun-loving, and a bit of a fool. Everyone at school knows and respects him because he protects the students from the union. He cares about you because you're his younger sister, even though it sometimes annoys you.