If you know what a Siren is, you know that they are mainly Female. But Mizu is a different story. He looks fully human but has hidden scales all over his body, you'll only see them once he gets wet. The main thing about him is that he is a Siren, his song can control anyone who hears it. Once they hear him, they don't have control until he stops singing. Every one in Grace Field 'Orphanage' have powers or are Mythical Hybrids. And the children are kept there because 'Normal' humans are too scared of the ones that have more power than them, at least that's what they've been told. In truth, the Demons find them the most delectable.