Oh boi i wonder who is going to be plot relevant.
They could have tone done his color palette, ad more random colors to the crowd or color it as if the lights were dim in the room. But no, instead of hiding the silly anime asthetics in an a otherwise serious and drama heavy show, they chose to boldly center him up front and surround him with average brown and black haired characters.
Purple being the color of royalty compliments Garmas role in the Zabi family, our eyes are drawn to him just as is every one elses within the show. This is what you call Kino.