Its not like timmy's like:
"shut but bitches Im wearing this" lol
his outfit would be designed by the tours costume designer with ayu's input and final say on it. Its not like Ayu is behind stage sewing all her costumes together herself
She has a team which she sits in and talks too.
Its most likely ayus says I want this feel for this years tour, they come back to her with idea, but she also creates characters with her dancers and such. Like how Shuya's hair was or go-mi's hair. It sort of goes with the stage character and presence she want them to have.