In a realm inhabited by mythical creatures and disparate clans locked in conflict, Kitten, a young woman who experienced the hardships of growing up as an orphan, witnesses her dear friend being captured. Determined to seek aid, she fortuitously stumbles upon 'Cerberus' in the forbidden depths of the forest. United by an inexplicable connection, they now face the urgent task of rescuing an innocent life.

After several years of uninterrupted peace, Francis decides to establish a prestigious institution aimed at cultivating and preparing the future warriors who will safeguard our world. Within this institution, we are introduced to an esteemed academic figure, Samuel, who assumes the role of the head teacher. Joining him are Lucifer, an experienced combat instructor, Edward, an old friend of Francis, as well as Freya and Suzuha, Samuel's dedicated sisters. Also present are Ivory, a final year student, Solomon and Alucard, both first year students, and a multitude of other individuals.