Blueprint Synthesizer

The monsters in the Secret Realm will not drop game loot, but a treasure chest of five different colors—diamond, gold, silver, bronze, and white—will be scattered everywhere, and it's up to the player's luck to have a fortuitous encounter with it.

The inhabitants of this world will not be able to see these chests, and only players do.

This 'everywhere' the author stated is not literally everywhere, Chests will be hidden where you least expected them to be, except for the white-grade chest. It was quite odd for one to just appear in the middle of the road, especially if it's a golden chest with the extreme rarity of 1/1,000,000.

If she remembered it correctly, whenever a secret realm opens, the number of players that manage to get their hands on golden chests would be less than 1% of the population of the players who ventured into the realm.