The top part (虍) looks like a 'tiger's head', and the bottom part (丘) is a 'hill'. Imagine a tiger roaring from a hollow hill, the sound echoing into an **empty void**.
'Kyo' — like a KYOto temple that feels perfectly still and **empty**.
'Munashii' — sounds like 'moon-ashy', like a dull, **empty** moon, making everything feel **vain**.