The Yakuza is a transnational criminal organization similar to mafia that originated in Japan.
At some point, Takeo Yamashiro and his brother Maseo met Tatsu Yamashiro, whose heart the brothers both competed for. Tatsu would eventually choose to marry Maseo, feeling rejected, Takeo refused to attend Maseo and Tatsu's wedding. Because of all this, Takeo joined the Yakuza, in which he rose through the ranks. Takeo later used that accumulated power to attack his brother's family. The entire family (save for Tatsu) would be massacred that same night. Tatsu took up her husband's blade and managed to defeat and kill Takeo.