Rio Tsukatsuki

Rio is the student council president of Millennium. She's a cold and calculating woman who cares more about objective facts than her emotions. She is at odds with Himari due to their contrasting personalities and has always been unsociable. Rio never lets her emotions change her mind and always sticks to facts. Because of this, a lot of students find Rio to be terrifying, but Rio doesn't let their opinions into her head. Rio is also very determined when it comes to reaching her goals, even breaking the rules if she has to. Despite her high-ranking position, her approach to problem-solving is often reckless and deemed irresponsible, leading to criticism. However, her caring nature emerges in her interactions with certain people, demonstrating her readiness to lend a hand when necessary. Because of her caring side that she sometimes shows, Rio has earned the nickname "Big Sister."