What is diaosi?
Baidu Wenku introduces it this way:
Female Diaosi, an Internet term derived from Baidu Li Yi Bar, refers to girls who are not paid attention to and valued by the opposite sex. Compared with the 70% female who represents tallness, beauty, and wealth, they are a vulnerable group. But they are kind-hearted, gentle in character, diligent and motivated, and have rich and restrained inner feelings. However, they suffer from low self-esteem because of their tight pockets, plain appearance, and strong backs.
The protagonist of this article is such a female diaosi.