It’s a corpse that burns itself AND the nearest person (granted it’s abusers and murderers but still)
In no fucking way is this thing safe to contain by keeping it in a normal storage. You need to make sure a D-Class is nearby at the time of burning, and to make sure the room is in a vacuum all the time to make sure the fire never goes off.
This is a classic case of keep it in the box, but always make sure the box works.