Hi! I'm new here ^^, and maybe I can help with a few things lol, at least with vocal fach... Wakana is a light lyric soprano for sure, her voice is very girly and light and bright, def placed higher than the others. Keiko is not a contralto as most people think, she's kinda a darker or heavier (not much tho) mezzo, def not a soprano, but neither a contralto. Hikaru is kinda hard to know since she changes her voice so much lol, adding more chest or head to her mix like that confuses me @.@ and her nasality too, but I think she's a light lyric mezzo since her voices does have more weight than Wakana and it's placed lower, but not as Keiko. Maybe I'm wrong with Hikaru tho... Kaori is a soprano, not sure what kind tho, her voice is light but less than Wakana. I must say, Wakana seems to be the best out of them all, she has some control in her mix, a few tension issues, and I think she uses head voice too sometimes. Hikaru is kinda a mess, sometimes she seems kinda pitchy (i suck with pitch tho lol), Keiko has really good E4s, she is pretty ok in the E4-A4 zone too, her lower notes seem kinda supported to me... she's a mezzo so, no wonder she can't hit C5s in full voice like Wakana does lol I'm sure she would strain them, their songs are kinda not very difficult for their skills, so they don't do anything they know they can't. I really love their voices too <3
I'll be back when I figure out how to put a dp lol