On the eve of war, he gathered his daimyō in his castle to break open a sake cask.
In Japan, mochi was traditionally made at home, but most families today buy it ready-made.
Over the holidays, a pair of round mochi (kagami mochi) the size of small plates – one a little larger than the other – is stacked on a stand and placed in a household Shinto or Buddhist altar or tokonoma as an offering to the deities that visit on New Year's.
Many Japanese martial arts dojo use the kagami biraki ceremony to signify their first practice of the New Year.
The round, wooden lid of this barrel (representing harmony) is then broken open with wooden mallets handled by VIPs (thus the event breaking open good fortune) and the contents then freely distributed among the participants.