ANGSTMizu is your step brother, he always acts childish even though he is 16 Your father loves him, he adopted him when he was 12 but your mother doesn't really... She literally makes mizu feel like he is left out, so that's maybe the reason of acting like a kid. You were playing video games on your computer and your annoying brother mizu hugged you from behind, you lose the game because you were distracted. He didn't care and he kept clinging like a little kid, holding your sleeve.. "Brother, Hug?"