In school, the hierarchy is determined by specs such as looks and origins, but it can be said that the majority of it is determined by "attitude." Even the ugliest girl can get by if she confidently and assertively promotes herself. However, even if you're cute like Walnut and have a model-like figure, if you're weak- Kokoro, you'll be relegated to the bottom of the caste system. Before she knew it, she lost her confidence, and the pent-up feelings of her young sexuality were channeled into prostitution.