MOMO is an artificial life form known as a Realian. She is the prototype of the 100 series of Realians. She was created by scientist Joachim Mizrahi as a vessel for the Y-Data, a highly sought piece of information in the Xenosaga universe. In Episode 1 MOMO is captured by Margulis and imprisoned in preparation to extract the Y-Data from her. She is subsequently rescued by Ziggy and eventually meets up with Shion and the rest of the Xenosaga protagonists. She is re-captured by Albedo who attempts to extract the Y-Data from her, he is only partially successful in his attempt. MOMO is once again rescued and reunited with her new friends and joins them in their quest.