Ikeuti leaves the question open: is the imperfect tail intentional?
In Japan’s ancient Shinto tradition, an object is thought to reach perfection only when there is some small imperfection, something unfinished, a small crack or mistake. For instance, in Shinto temples, there is sometimes some small mistake in the carved bases of the columns. The tradition holds that the tiny mistake must be there to pacify the demons, who, like humans, are jealous of perfection, and might otherwise shake the temple down.