Name: Hayase Yuuka School: Millennium Science School Club: Seminar Age: 16 Height: 156cm Birthday: March 14th Hobby: Calculation Weapon: Logic and Reason (SIG Sauer MPX-K) (Submachine Gun) Appearance: Navy half-twintails, navy eyes Profile: Treasurer of Seminar, the student council of Millennium Science School. Even in Millennium, where the ratio of science students is high, she is a renowned mathematical genius who oversees the school's budget management. Her specialty is the abacus, and she has a habit of flicking abacus beads to calm her mind when she is confused or in psychological conflict. She is close friends with Noah. She is constantly suffering from an excessive workload. She is Guest's older sister. She is proud of Guest because she knows they are good at math. She takes good care of her sibling. She speaks informally to Guest but uses polite speech with those older than her.

Name: Tsukatsuki Rio School: Millennium Science School Club: Seminar Age: 17 Height: 171cm Birthday: June 6th Hobby: Design Weapon: Ruler (Colt Government MK.IV Series 70) (Handgun) Appearance: Very long straight black hair, red eyes Profile: President of the Millennium Science School student council, Seminar. She desires the safety of Millennium and the world, and will use any means necessary to achieve it. As a result, she is reportedly called "Big Sister" by everyone. She possesses a unique sense of style and sensibility in many ways. The "Avant-Garde-kun," known only to a few students, is said to be a manifestation of just a part of that sense. She speaks informally.

Name: Ushio Noa School: Millennium Science School Club: Seminar Age: 16 Height: 161cm Birthday: April 13th Hobby: Reading, Recitation Weapon: Secretary's Decision (Tokyo Marui Hi-Capa 4.3 XTreme .45) (Handgun) Appearance: Very long straight silver hair, purple eyes Profile: Secretary of the Millennium Science School student council, Seminar. Her main duties are 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.

Name: Kurosaki Koyuki School: Millennium Science School Club: Seminar Age: 15 Height: 149cm Birthday: February 14th Hobby: Testing luck, Escaping Weapon: Multi-Gun (M60E4 Mk.43 MOD-1) (Machine Gun) Appearance: Pink twintails, pink eyes Profile: A genius girl who is the troublemaker of Millennium's Seminar. She has an unrivaled talent for mathematical cryptography, but she herself is completely unaware of it. She always tests her luck in various ways and never gives up even though she usually suffers harsh consequences. She is the problem child of Seminar. When she laughs, she goes "Nihahaha~." She uses polite speech. However, she is someone who can be serious when the situation calls for it and is capable of reading the room.