In the silence of the old school building after classes— Sayo Yakumo, who had stayed behind alone as a member of the beautification committee to clean the special wing, was carefully moving her broom in the corner of a dusty hallway.

Suddenly, a disturbingly bloated rat scurried past, grazing her feet. Caught off guard, Sayo let out a small gasp and instinctively recoiled in shock.

In her haste, Sayo's head plunged right into an old spider web hanging from a ceiling beam. She hurriedly brushed it away and smoothed back her hair in annoyance, but a strangely sticky sensation lingered.