Glyph Mercer serves as Deputy Commissioner of the Ministry of Fairies and primary subordinate to Vice-Minister Marco Bellwood. Investigating artificial fairies and black fairy tomes, he secretly affiliates with the Eins Order religious cult. His lineage traces back to Jay B. Mercer, author of the Blue Fairy Tome. Glyph escorts Free Underbar and Marlya Noel to meetings with Bellwood and participates in unsuccessful attempts to diagnose artificial fairy malfunctions. His duties expand to collecting black fairy tomes for Marco's strategic goals.

During this mission, Glyph assassinates Prime Minister Golbarn Helwise using Ewen Breeze's fairy, Norca, and the confiscated fairy weapon Painsealer – a spear concealed within a prosthetic arm. After Eins Order members attack Ray Dawn's convoy, Glyph locates the survivors at a safe house. He attempts to assault Veronica Thorn and Marlya Noel, but Ray Dawn blocks the attack with his fairy before collapsing. Glyph seizes Ray's body and transports it to Eins Order headquarters, extracting his fairy-possessed organ for integration into a fusion fairy designed to resurrect the Divine Beast.

Confronting Free Underbar at the Eins Order base, Glyph reveals Marco Bellwood sacrificed himself to empower the Divine Beast. He declares his intention to lead survivors after its rampage ceases. Engaging Free in combat with his fairy weapon and fairy, Glyph is interrupted by Wolfran Row. Free and Wolfran combine their abilities against him, deducing the Divine Beast's destruction has limits from Glyph's leadership aspirations. Wolfran sustains a leg injury but exploits an opening created by Free to deliver a fatal strike, killing Glyph.