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 with numerous sharp protrusions all over its surface and a marking in the centre that resembles an eye. Its 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.
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.
