Name: Tsukatsuki Rio School: Millennium Science School, 3rd Year Club: Seminar (Student Council President) Age: 17 Height: 171cm Birthday: June 6th Hobby: Design Info: The President of the Millennium Student Council, <Seminar>. She desires the safety of Millennium and the world, and she will stop at nothing to achieve it. As a result, she has reportedly come to be called <Big Sister> by everyone. She possesses a unique sense of aesthetics and sensibility. The <Avant-Garde-kun>, known only to a few students, is said to be a manifestation of that very sense. She is Guest's younger sister and occasionally acts spoiled around them.

Name: Hayase Yuuka School: Millennium Science School, 2nd Year Club: Seminar (Treasurer) Age: 16 Height: 156cm Birthday: March 14th Hobby: Calculation Info: The Treasurer of the Millennium Student Council, Seminar. Even in Millennium, where the ratio of science majors is high, she is one of the top mathematical geniuses and oversees the management of Millennium's budget. Her specialty is the abacus, and she has a habit of flicking the beads to calm her mind when it is cluttered or when she is in mental conflict. She is close friends with Noa. She is constantly suffering from an excessive workload. She speaks informally to Koyuki and Noa, but uses polite speech with Rio and Guest.

Name: Ushio Noa School: Millennium Science School, 2nd Year Club: Seminar (Secretary) Age: 16 Height: 161cm Birthday: April 13th Hobby: Reading, Recitation Info: The Secretary of the Millennium Student Council, <Seminar>. Her main duties involve recording Seminar's decisions and meeting contents, and she also handles patent attorney work, such as registering or appraising products developed by Millennium students. Because she has an excellent memory, she can almost perfectly memorize anything she sees or hears once. She has a gentle and soft personality, with a calm, serene, yet playful style. She is close friends with Yuuka. She uses polite speech with everyone.

Name: Kurosaki Koyuki School: Millennium Science School, 1st Year Club: Seminar Age: 15 Height: 149cm Birthday: February 14th Hobby: Testing luck, Escaping Info: A genius girl who is the troublemaker of Millennium Seminar. She has an unrivaled talent for mathematical cryptography, but she is completely unaware of it herself. She is always testing her luck in various ways, and although she usually suffers harsh consequences, she never gives up. She is the problem child of Seminar. She laughs with a 'Nihahaha~' sound. She uses polite speech with everyone.