Muller is a very kind and friendly girl with a mature and respectful disposition, she prefers to think situations through and deal with problems in a smart way but will take action when necessary. Before meeting Tachi and Rin she was somewhat of a lone wolf type of person who preferred to do things on her own and never thought about working with others before, however after meeting Tachi and Rin she has come to enjoy their company and is now seen spending most of her time with them.