I’d like to contribute!
For my main cast, the design choice for them is usually a mix of their personality, interests, and personal history.
Raveena Vesper usually has a cool, boyish look with some punk influence. Her very first original design leaned more toward a cyberpunk-ish vibe, but it was eventually simplified to fit the webnovel, where she's an aspiring engineer. She's highly intelligent, has a quiet and reserved personality, and has trouble trusting people easily, so darker colors suit her well.
My wife, who designed Raveena, is currently developing a new look for her that leans more heavily into alternative fashion. It fits the personality Raveena develops later in the story much better.

Aya Ribbuns is much more straightforward. She prefers cute, bright, pastel-colored clothing because it matches her sweet personality. She’s gentle, supportive, a bit of an airhead, and very much the “cinnamon roll” of the group. Her personality is also highly inspired by Sanrio's My Melody.
Some parts of her personality and design are also inspired by rabbits, since she is rabbit-folk.

Mizu Angel was the most difficult character for me to develop. She’s technically a student like the others, but she’s also an actual doctor, a master of magic, and an extremely intelligent character.
Her clothing is intentionally eccentric and a little hard to process at first glance. So to pair with that idea, I gave her the eerie, strange impression she gives people. Despite that, she’s a genuinely caring friend, even if she tries very hard not to look like one.
Her design was created by a friend and loosely inspired by the Cheshire Cat. The outfit originally came from their personal design tastes, so I later built Mizu’s personality around that strange appearance.

Lastly, Rory Brixton has a more casual and neutral wardrobe. Her colors are easy on the eyes, while also matching her red fox traits.
She’s the social butterfly of the group: cheerful, outgoing, playful, and occasionally a little dumb for comedic purposes. Her clothes are simple because her personality already does a lot of the storytelling for her.
