Tbh I don't see a place where you should improve. (I'm starting to think this was a joke, but me beeing super hyped about it, I didn't realize it. Anyway...) Your shadowing is perfect, the animation makes you look like you are a creactor of some real anime. (If so I'm really gonna flip, knowing someone like you asked for oppinion from someone like me!
The characters are perfect for anime standarts, but I'd like to know how your art would look like if you'd drew a realistic one. I'm geniuely curious. The body structure is flawless and so is hair.
I'm getting a bit carried away, but that's really all I can say. If you're not a creator of an anime you should consider beeing one. Also you should seek advice from a more, more professional artist not an amateur like me, because your art is a really, really high standart art and if I'd even try to critisize your art, I'd feel like I'm disrespecting you and every artist ever. And looking at my art, I think i have no rights to critisize yours.
(If this wasn't a joke or anything, I am truly honored that you came to me for an opinion, and I'm also sorry I couldn't actually do much)