Here's their personalities:
Kaisa is a 15 year old naive moe. She is very clueless when it comes to reality and stuff, and has a tsundere crush on Atashi. She is mostly a shy person around crowds but can be loud at times.
Kohana & Subarashii Niji are both twins, well pink haired twins. Both are 13 years old (probably in freshman class). Kohana is a girly girl yet, can be mean to others at times. She is a very happy person. Subarashii is more of a regualar type of girl, and is nice to others. Both can be abusesive at times and inseparable.