Guren no Ōdachi (紅蓮の大太刀, Great Blade of Crimson) is an offensive Unrestricted Spell acquired by Shana during her late-night training. It manifests flames in a huge, sword-like shape to burn and cut opponents. To aid in her visualization in order to construct the manifestation, she would often coil her flames around the long sword Treasure Tool Nietono no Shana, but she could accomplish the manifestation bare-handed.
In the fight against Fecor, Shana demonstrated a new way of using it. Unlike previously where she was causing explosions by emitting flames, its form was at a very high temperature to the point of melting and was almost solid. The formed blade was several times taller than Shana herself.
Shana didn't name this Unrestricted Spell when it was in its early stages, and simply called it the Ōdachi (大太刀, Great Blade).
- The name "Guren no Ōdachi" comes from the narrative, and was never named by Shana.