From Wataame Shoujo:
Suh-Ah is a quiet and reserved high school girl who almost seems unapproachable. One fine Saturday after school, Suh-Ah is dragged into a "meeting" with boys from the neighboring highschool because one of the girls gets sick.
Fate lands the well-known "king card" (Hwan) on her lap and she immediately says good bye and goes home. This incident hurts Hwan's pride and haunts him, to the point that he has to see Suh-Ah again...

Nareh and Tareh are fraternal twins, Nareh the elder sister and Tareh the younger brother. When Nareh learns that Tareh has been accepted into the all-boys Ordinary School, she is shocked, and prepared to stop him at all costs...