Granda is a Yin-Self Horror which is one of the nine Horrors freed from the slate that uses their malice to seal the legendary Horror Eyrith. It is able to flee into pocket dimensions.
Granda is freed from the Ady Slate when a mysterious person destroy the slate using Madou Art technique. It's appearance and host is unknown but it possess the power to move in pocket dimensions. After appearing, It is detected by the watchdogs and it fled into the pocket dimension. The watchdogs know it will appear on a rooftop of a building next but not when.
After being detected by the watchdogs, Raiga is sent after Granda. After waiting at the location, Granda is detected and it's identity as a slab horror is revealed by Mayuri. It is stopped by and sealed with its essence congregates into a stone that Mayuri absorbs to seal the Horror.
It is able to travel into pocket dimensions. It is also able to multiply into many copies of itself, albeit the copies will crash against each other.
In the series storyline, Granda is the 4th of the nine Horrors used as the foundation to seal Eyrith in the Ady Slate to be captured, though it is not the carrier of Eyrith's seed.