Akashi is a Cat in disguise, a thesis
Akashi is often liken to a cat, but I think most people underestimate how much of a cat he really is.
First the obvious, he has cat eyes
The way he stare unblinking at people when he analyze them. That's what cats do.
The slow blinks he does, it's exactly what cats do to show affection. I'm sure you remember how many times we see Akashi blink in slow motion in the anime.
Exactly the way cats look when they're hunting or playing, even the stillness -> sudden movement
Cats are small but they jump high, he is 5′ 8″ and he can dunk
Let's be honest, if our cat could do that to us they would
And last of all, look at him, is he not an adorable kitten ??
He also does this thing cats do, when they just sit next to you and follow you if you leave the room. Like they want to enjoy your company but not really interact at time.
EDIT : I FORGOT A VERY IMPORTANT POINT
The way he wins many competitions (during the summer festival and the teiko school festival) and brings all his prizes to Murasakibara like a cat brings its hunting trophies to its owner
That's all for now, I probably forgot a few points and couldn't illustrate others but I think I gave enough examples for my thesis.
In short Akashi is a cat, but not only that, he is the most adorable kitten to ever exist.