>>104161942
tldr Kiara was supposed to be part of jp5, with a Phoenix character called Nazca due to the bird Nazca lines and Asuka.
It is wholly possible the hair is a nod to this Asuka.
Re Shioria and Luca, Shiori likes nuns so it might be a coincidence, but it's also true that they draw from the same archetype. Shiori first and third outfit are based on her own fashion sense.