Shizuki Ugaya, grandmother of Tamaki Kasuga and former Tamayori Princess, bears the hereditary duty of sealing the supernatural blade Onikirimaru. Stationed in Kifumura village, she safeguards the sword with aid from five guardians until transferring this role to Tamaki. Revered as "Baba-sama" by the guardians sworn to protect the Tamayori Princess, Shizuki’s lineage binds her directly to Tamaki, whose sacred bloodline mandates inheriting the perilous legacy.

When Tamaki arrives in Kifumura, Shizuki reveals their family’s ancient burden: maintaining Onikirimaru’s seal through generations while confronting supernatural threats tied to its power. The role demands spiritual mastery—crafting barriers, repelling dangers—and personal sacrifice, drawing strength from ancestral forces. Though specifics of Shizuki’s tenure remain sparse, her authority is evident through Mitsuru Kotokura, her attendant from the Kotokura branch of the Ugaya family. Mitsuru oversees Shizuki’s daily needs and ceremonial tasks, reinforcing her revered position in the village’s spiritual order. Shizuki embodies a resolute mentor, steering Tamaki through the weight of tradition and duty with stoic resolve.