The fire-hiding glass crafts in "Metaphorical Fantasy: ReFantazio" are special props that are useful at certain times in the game. If you want to get this fire-laying glass crafts, you can explore the ancient well dead end during the day on July 8. Then open the treasure chest in the southeast of the map in Decaying Waterway 6.
How to obtain the glass crafts that allude to fantasy and fire
July 8th, daytime, explore the dead end of the ancient well, the plot, the decaying waterway 06/06, save people first and then open the treasure chest, otherwise you will be forced back to the center of the map.
Open the treasure chest in the southeast of the map to find a glass craft with a hidden fire inside.