From JShoujo Scans:

High school girl Kurei-chan attends an all-girls school that is located near two other high schools. The other high schools are famous for their gang leaders, the Black leader and the White leader. Kurei, who is more obsessed with sale specials, decides to jump over a wall to go to the next sale faster. Unfortunately, she jumps in to the middle of a fight between Blacks and Whites. The fight stopps to have a look at her. Kurei, scared, tries to back away. With no way to go, a guy appears who looks like he is there to help her, but is actually there to join the fight. Shocked, Kurei now wants to run away, but is more annoyed that her groceries are stepped on, yelling at them for being idiots. The guy picks up the groceries for her bravery, and gets her to hop onto a bike to get away from the fight. The guy is Kuroki, the Blacks' leader. The White leader sees it all, and decides to play a game. What will happen to Kurei now?