Although it is said that four keys are needed to open the door in the "Gravel Golden Sea," the number is not much at all, as similar Divine Items or Symbols are easy to find.
"Earth" has the little clay cat figurine given by Vanessa, and "Sun" can be represented by little Mia, who carries the bloodline of the "Son of the Sun." This was exactly what Shard did at the "Gadis Library." Although there isn't a concrete plan for "Moon" and "Brightness," the time is ripe for the appearance of "Brightness's" The Chosen One. There are plenty of items related to that Ancient God here.
"Those three Dragon Scales would work, but the issue is we're unsure if you can bring the Dragon Scales back; they're too important to risk."
In the garden behind the manor, Luviya sits at a table under the grape arbor, watching Emilia and Angelina and the two Miss Maids grooming the Little Unicorn in the distance while speaking to Shard:
