It is the default weapon of New Year's Takumi.
Accelerates Special trigger (cooldown count-1).
Kagami Mochi is a Japanese traditional New Years decoration. It is usually made by two pieces of Mochi with one being smaller and placed on top the larger one. A mikan orange is then placed on top of the Mochi. The build is then placed on top of a sanpō stand and placed in the home. The structure is meant to ward off fires from the home.