Muramasa is a sword spirit partnered with Shuri Kijino at Fujimisaki Academy.
This Z/X manifests as a humanoid female entity with distinctive hair buns, classified as an inanimate object manifestation.
Muramasa declares pride in her combat philosophy: facing a warrior with weapons signifies death.
She forms a close bond with Shuri, fighting interdimensional threats called Inerma as part of an E-rank team.

Her combat capabilities include the Void Bringer ability, removing opposing Z/X from battle under specific life point conditions.
The Ignition trait allows her to retrieve other "Muramasa" cards from the discard zone and draw cards when Shuri enters Overboost.
An evolved form, Sorrowful Spirit, Muramasa, disrupts opponent resources and enables deploying Shuri's enhanced transformation card without cost when sufficient resources accumulate.

During the final conflict, synchronization with Shuri achieves an Overboost transformation.
This fusion merges their strengths into a single powerful entity, reflecting deepened trust and combat synergy.
Throughout official media, Muramasa's narrative centers on her steadfast partnership with Shuri and martial dedication.