It seems that many anime lately, specially bishoujo, have a ojousama. To Heart, for instance, has Kurosegawa Serika. Well, Reiko is Kakyuusei's ojousama.

Reiko has the, ahem, bitchy attitude of some ojousama. She thinks she is superior to everyone. However, Tsuyoshi does not let Reiko treat him like that, but rather as similars. Her episode is episode 8.

She only makes a small cameo in the OVA, saying a line. To say the least, she is at the bottom of my fav Kakyuusei female characters.

Note: "ojousama" is usually referred to the 'debutante' high society girls.