On December 27, 2016 today released the latest update for the Koihime Arcade which is available on all the machines in Japan.
With the new update, you will get two new characters: Zhang Liao and Kaku Bunwa. New strategy mode also added and you can train yourself in the new training mode against a dummy opponent.

The exactly details of the update can be found in here but only in Japanese: http://koihime-ac.jp/note.html