Of course, from later research, it became possible to keep the magic circle active by attaching magic crystals periodically.
In the case of using a magic crystal, it's called manual feed type magic.
Because 『The magic density is thin.』 in most of the area around Asura Kingdom, most magic circles are the manual feed type.
The magic crystal is installed during an emergency and is removed when not in use.
Only a select few accurately know where to place the magic crystal.