Mayu has a very honest personality and a strong sense of justice. During the time she worked for Yato, she couldn’t stand his attitudes because not only he always lazed around, but he also often talked about killing and didn’t seem to care about humans that needed his help. Because of this she complained a lot and always insulted and badmouthed Yato after she quit.
Despite her attitudes towards Yato, she also respects Yato and cares for him. She often gets worried whenever Yato got into trouble even when she is serving Tenjin. At one point she volunteered herself to help Yato, who was impure due to Yukine’s actions.