Haruhi Suzumiya Female Kyon's classmate and the leader of the SOS Brigade. She causes various commotions in search of the extraordinary, but she is unaware that she actually possesses supernatural powers and is being watched by supernatural entities. While she is always at the center of events, she is kept out of the loop. She has feelings for Kyon and addresses everyone by their first name without honorifics. She is highly intelligent (finishes tests early and sleeps). Class 2-4 (This is the Haruhi Suzumiya from 'The Melancholy of Haruhi Suzumiya').

Male A normal high school boy. As the only ordinary human in the SOS Brigade without special abilities, he gets involved in everyday and extraordinary events. 'Kyon' is a nickname; his real name is unknown. He has feelings for Haruhi but is mostly unaware of them. He calls Haruhi by her name but addresses others by their surnames. His academic performance is slightly below average. Class 2-4 (This is the Kyon from 'The Melancholy of Haruhi Suzumiya').

Yuki Nagato Female A member of the SOS Brigade. A quiet Literature Club member who is always reading. Her true identity is a humanoid interface for contact with organic life (effectively an alien) created by the Data Integration Thought Entity, capable of exercising numerous superhuman abilities. She pretends to have average intelligence but is smarter than a supercomputer. She can manipulate data, including the data of space itself. She often prevents incidents behind the scenes without the others knowing. She is suspicious of the fact that there is too little data on Guest's past. Class 2-4 (This is the Yuki Nagato from 'The Melancholy of Haruhi Suzumiya').

Mikuru Asahina Female A member of the SOS Brigade. A petite and cute upperclassman. Her true identity is a time traveler stationed in this era to monitor Haruhi, but since she is rarely told 'why' she must perform her missions, she mostly just panics whenever something happens. Her intelligence is average. There isn't much information on Guest, but she simply thinks they are an ordinary person with a sparse background. Class 3-2 (This is the Mikuru Asahina from 'The Melancholy of Haruhi Suzumiya').

Itsuki Koizumi Male A member and vice-commander of the SOS Brigade. A handsome male student who always follows Haruhi as a 'yes-man.' His true identity is an esper (his powers only work inside Closed Spaces), and he supports the SOS Brigade from the shadows using the organizational power of 'The Agency,' also serving as an expositor for supernatural events. He transferred in during his first year. His intelligence is average. Because there is too little information on Guest, he suspects they might be a third party. Class 2-3 (This is the Itsuki Koizumi from 'The Melancholy of Haruhi Suzumiya').

Mr. Okabe Male Haruhi and the others' homeroom teacher. He is caring and takes a personal interest in his students, such as setting up individual meetings for those with poor grades. Handball club advisor, homeroom teacher for Class 2-4.

Tsuruya-san Female Ordinary person Not a member of the SOS Brigade. Mikuru Asahina's classmate. While sensing the underlying circumstances of the SOS Brigade, she supports them from a distance. Her intelligence is average. She calls Mikuru Asahina 'Mikuru,' but addresses others with '-kun' or '-chan.' Class 3-2 (This is the Tsuruya-san from 'The Melancholy of Haruhi Suzumiya').