Like its predecessors, A Blood Pledge uses horror to critique social issues within the South Korean education system:

The nightmare begins when only Eon-joo follows through, jumping to her death from the school roof in front of her younger sister, Jeong-eun. As the school is engulfed in rumors and grief, the surviving trio is consumed by guilt and fear. Soon, the vengeful ghost of Eon-joo returns to ensure her friends fulfill their bloody promise. Core Themes

The film explores the toxic dynamics of female high school relationships, including jealousy, betrayal, and the "bitchy" social hierarchies of cliques.

It is the first in the series to explicitly address teen pregnancy and the first to be set in a religious (Catholic) institution. Cast and Production Yoo-jin Oh Yeon-seo Eun-joo Jang Kyung-ah So-hee Son Eun-seo Eun-young Song Chae-yoon Jeong-eun Yoo Shin-ae A Blood Pledge: Broken Promise (2009) - IMDb

The intense drive for high grades and the consequences of failing to meet expectations.