Emma Kliesen is the deceased mother of Leo. Leo can be seen visiting her grave and placing flowers upon it in the Tekken 6 opening movie. She appears once again in Steve's Tekken Tag Tournament 2 ending comforting him after he was injected and tested by scientists from the Mishima Zaibatsu. In Leo's ending in Tekken Tag Tournament 2 she is mentioned once again. Apparently she had been a supervisor for the Mishima Zaibatsu's Devil Gene program. The program was cancelled due to the death of it's test subjects. Emma had also falsely reported the death of NT01. She was murdered between Tekken 5 and Tekken 6, which left Leo believing that Kazuya Mishima was responsible for her death, and seeking to avenge her.
- Wife of Leo's father.
- Mother of Leo Kliesen.
- Presumably killed by Kazuya Mishima before Tekken 6.
- Had apparently taken care of Steve Fox as a child when he was being experimented on in his Tekken Tag Tournament 2 ending.