She is Kazuki's girlfriend as well.
Moriko first appears in the Way of the Warrior when she fights against Akiko in the competition between the two Samurai schools. In the taijutsu segment versus Akiko, she cheats and no one could spot her illegal acts. She goes on to win the duel which angers Jack due to her cheating.
In the Way of the Dragon, Moriko joins in with the attack on the Samurai school of Niten Ichi Ryu, led by Kazuki. She attempts to kill Akiko with her arrows, but is winded by the latter's jindou. She dies when the burning building collapses on her and Kazuki blames Jack for her death even though it is not really his fault.
Moriko's defining feature is the fact that she has black teeth. She has a vicious and competitive streak and is willing to use underhanded methods to win, as shown in the Way of the Warrior, when she is fighting against Akiko.