Mii

Mi was a Human child that was saved by Zero Kiryu.

History
Mii's grandmother used to call her 'Mii-chan'.

Plot
Mii was shopping with her grandmother when she was kidnapped by a vampire. She was hiding and sobbing while Zero was trying to recuse her. At first she was scared of him, but he then tried to comfort her by telling he that he took care of the bad man. Zero then carried Mii to her grandmother, and before they were able to thank him, he left without a trace.

Many years decades later, when Mii was out with her grandchild and husband, she recognised Zero. She asked him if he was related to the man that saved her many years ago, as she had always wanted to show him her gratitude for saving her. Zero replied that he wasn't and apologized for not being of any help. As she walked away, Zero was shocked to see that she had remembered him after so many years. Yuki commented that is was good that Mii got to live a happy life thanks to Zero.