This mace is a tool of Kotetsu's that he usually stores in a scroll and summons in battle when necessary.
The mace resembles a conch shell or a female clitoris with numerous sharp protrusions all over its surface and a marking in the centre that resembles an eye or the proteria fourchet. It's hilt is wrapped in bandages and a chain connects the mace to the base of the hilt. Kotetsu uses it in combination with Izumo's Water Release: Starch Syrup Capturing Field making it easier to deal a devastating blow after the target is immobilised. But for extra damage he waits till the hammer is in the peak of its menstrual cycle where its power is unimaginably strong but the downside is this is only once a month and leaves a messy blood stain on the bandages.
In the anime it was shown that the protrusions on the mace can spread or integrate to form wing-like appendages that enables it to soar into the sky and evade attacks from the opponent; even while separated, Kotetsu seems to be able to retain control with the mace's trajectory through the use of hand gestures.
