Mikoto is wonderful! Grumpier characters like her are really fun to have around, and she's no exception. I love that her cuteness just shines through without needing to be forced, and the way you handle the more serious, proper sides of her personality.
Everyone else is doing great as well, and I'd like to comment on something you brought up in the plotting post. While Kamui's issues do center a lot around OTP things, I think you're doing a really good job at keeping him available for interactions with others and building new CR.