According to other sources, like post #536255, it was Meiling who taught Sakuya to wear twin braids.
This idea is almost as adorable.
A braid story, part 2Because I admire Sakuya,I braided my hair like this.If Sakuya unbraids hers, I'll unbraid mine. If she cuts hers, I'll cut mine.This braid is like a visible connection with Sakuya ….I— I won't lose!