The top one is Crona's sex so it's what he biologically is. Gender is what YOU process as. Crona has never clarified for us so yes it is unknown. Either way Crona is still my favorite. Right above Kid.
Noragami, Ouran high school host club, Attack on titan, Sword art online XD (I'm so doing something like this to my future kids) first thing i would say would be like "Im so sorry kids but your named after anime and manga characters"