[shuuu]

This is Squalo, Kozatu's demon. She was basically unheard or ignored for most of her life, so this is where Squalo comes in.
He just too different not to be noticed. In fact, most wishes made on demon bonds have an ironic twist to them.

Most demons are just different versions of the host. Either by design or personality. Most are different genders too.

Also, I'm pretty sure Squalo means Shark ovo