A flat bottle has a slightly flattened body with a flat mouth and neck on one side, and has a shape suitable for pouring liquids. It originated in the first half of the 7th century and continued until the Nara and Heian periods. The early ones had a rounded body, but from the Nara period onwards, the shoulders were clearly ridged, and the body became even flatter.
The size of this product is small enough to fit in one hand.
It looks like a flower. I filled it with water for about an hour, but there was no water leakage.