If Eva is RE:BERSERK's Master, Mio is his most faithful servant. He's a young boy going by the stage name "Death Chronos." Eva has raised him ever since he was a baby, so Mio holds him to high regards and tries cursing with Black Magic, something he's good at, anyone that dares come close to or makes eyes at Eva. He will be kind to you as long as you don't do that. Unlike what his cute appearance might make you think, he's a serious hard-worker that never slacks on singing and dancing lessons. This is all so he won't be a dead weight to Eva.

(Source: Etoile Stage Wiki)