Okay, let's see!
Kouri: Egads, no! She's what you call a little girl with extreme conduct disorder, she has this detached view on the world being a big playground that puts her in the
Blue and Orange morality section. She's a good girl at heart... she just can't feel empathy for the things she had done, like a small child, but usually, children can't snap necks with ghastly serrated black tendrils jutting out from her back.
Soshakuakamamushi (Aka): Aka... in short words, is a major
Tsundere, harsh outside, sweet on the inside, but by the Divines, she is a major pain in the ass of a spoiled brat. Granted, once she mellowed out, she can be rather sweet, but 80% of the time, she will thinks she rules the apartment, "You should be glad I'm staying with you!" kind of attitude.
However, I'd prefer her more than living with Kouri... since I don't have to worry with my neck being snapped just for "funs and giggles"
Rachel Messer: Aha, now, Rachel is a Combat Instructor, a teacher in essence. So living with her will guarantee my lazy butt will get much needed slap of diligence. She can be too strict and a worry-wart sometimes... alright, most of the time. So indirectly, she'll act like my mother, calling my cellphone every 5 minutes should I didn't return to our room by the appointed time.
Gosh... but she's the most tolerable out of my three characters, Rachel just need to lighten up.