Sacred form is the true form of person. Sacred forms show the true face of a person, of their soul. These forms portrait the person as an animal but keeping their body human like (2 legs and 2 arms are common, more limbs are rare). Person's personality can be easily guessed in this form (ex.: rabbit: coward, innocent ; wolf: loner, aggressive ; eagle: brave, feared). This form also gives the person abilities. If their form is based on a bird, they will have wings and can fly. They're great fliers and acrobats, they're feared in the air but they're weak to bullets, electricity and are clumsy and easy prey on ground. If their form is based on a reptile, they can hold their breath for a very long time, some of them are great at swimming (crocodiles), some are better at running (lizard). Animals with fur can survive better in cold, clawed animals are great diggers and cave finders. Yeah, I guess you get it what I'm trying to explain here. This form is not used very often anymore though. It has become forsaken after the rebels have taken over the goverment and are ruling most of the planet (fuck me I'm spoiling shit). People are not allowed to show their true forms in public or they will be shot. Runaways are being searched for by hunters and are sold to goverment if captured. They're used for hunting other runaways, experiments or just fun (skinning something alive isn't fun but yeah). New generations are not able to use their sacred forms anymore (they don't have a gene that is used to activate the sacred form because they don't really need to use it anymore).

Kio's based off an eagle. He's a great flier, flies very fast and when spotted (happens rarely), he cannot be caught while in the air.
His wings are too big so he can't fold them. They just hang down like arms and are being carried all over the place (he's like a broom haha) making his wings very dirty from time to time. They're also very sensitive so any wound troubles him with flight.
Kio has powerful legs, his kick can smash a skull so even though he's very vulnerable on the ground, he can still fight until his last breath.
And his beak is really sharp. Seriously, don't mess with him.