- Ryoko Asakura (朝倉 涼子, Asakura Ryōko)
- Voiced by: Natsuko Kuwatani (Japanese); Bridget Hoffman (English)
- Ryoko is Yuki's backup and, as such, is another "humanoid interface." Like Yuki, she finds it difficult to empathize with humans. Unlike Yuki, she possesses exceptional social skills, and successfully passes herself off as a compassionate and hard-working high school girl. Her enormous popularity made her the unanimous choice for class president of Kyon's homeroom. She is unable to befriend Haruhi in order to better observe her, so when she notices Kyon successfully interacting with Haruhi, she encourages him to "open her up to the class". She later tries to kill Kyon with a combat knife in the hopes of catalyzing an observable reaction from Haruhi. Yuki stops her and removes her from the school, using the cover story that Ryoko moved to Canada. Ryoko returns in the light novel The Surprise of Haruhi Suzumiya, fulfilling her role as Yuki's backup when Yuki is disabled by the Heavenly Canopy Domain. However, the Data Integration Thought Entity still regards her as a risk due to her attempt to kill Kyon, and she is given limited authority to act.
- An alternate version of Ryoko appears in The Disappearance of Haruhi Suzumiya. In this story Yuki alters reality to make herself a normal human, and remakes Ryoko into a protector for her. She is destroyed by another Yuki that came from a few months later in order to restore reality to its former state.
- In the spin-off miniseries The Melancholy of Haruhi-chan Suzumiya, she appears as a chibi form dubbed 'Achakura' as the result of a failed reincarnation, and moves in with Yuki after she saves Achakura from a cat. She is subject to pranks from Yuki, such as being transported around in a baby carrier or dressed up like a Hinamatsuri doll. In Nyorōn Churuya-san, her appearance is similar to Tsuruya/Churuya and she has a crush on Kyon. She is one of the main characters in the spin-off manga, The Disappearance of Nagato Yuki-chan. In Yuki-chan, she has none of her psychopathic tendencies, and instead serves as a neighbour and sisterly/motherly figure for Nagato - doing things like waking her up and making her dinner. In this reality, she actually does move to Canada to study.
- Tsuruya (鶴屋)
- Voiced by: Yuki Matsuoka (Japanese); Kari Wahlgren (English)
- Tsuruya is the hyperactive friend of Mikuru (from the current time plane) recognizable by her loud voice, calf-length hair, and prominent upper canine. Her canine gives her an idiosyncratic speech pattern, causing her to misspeak by leaving out syllables. Her speech pattern is often accompanied with a lisp and her catch phrases "megas" and "nyoro". She has a cheerful and friendly disposition. She is prone to long fits of unrestrained and intense laughter at things she considers even the slightest bit humorous. She is the heiress of the wealthy and venerable Tsuruya family, which purportedly collaborates with Itsuki's Agency.
- Though not a member of the SOS Brigade, Tsuruya is used as an extra body for some of their activities, playing a minor role in "The Adventures of Mikuru Asahina Episode 00" and serving on their baseball team in "The Boredom of Haruhi Suzumiya". She appears sparingly in the anime, but takes on more prominent roles in some of the novels not adapted into anime. In these she confides to Kyon that she is vaguely aware of the SOS Brigade's supernatural nature, but prefers to be involved with them only peripherally. Tsuruya takes care of Mikuru when the latter has a double presence in the 'present' and is the caretaker of a mysterious artifact discovered on her family's grounds, both at Kyon's request.
- In the altered reality of The Disappearance of Haruhi Suzumiya, and retaining the character for the spin-off manga The Disappearance of Nagato Yuki-chan, Tsuruya's role is that of Mikuru Asahina's best friend. She is extremely protective of her, but still maintains her cheerful disposition. She is the star of the official gag manga, Nyorōn Churuya-san, featuring a super deformed Tsuruya with a smoked cheese obsession, which later became an anime mini-series. She makes appearances in The Melancholy of Haruhi-chan Suzumiya where she apparently has a rivalry with Sonou Mori.
- Taniguchi (谷口)
- Voiced by: Minoru Shiraishi (Japanese); Sam Riegel (English)
- Taniguchi is a classmate and friend of Kyon. Taniguchi went to the same junior high school as Haruhi while Kunikida went to the same junior high school as Kyon. Like Tsuruya and Kyon's sister, they act as fill-in members for the SOS Brigade when needed. Both of them play small parts in The Adventures of Mikuru Asahina Episode 00. They are friends and are almost always seen together.
- Taniguchi is comically lecherous; he gave a 'score' of attractiveness to each first-year girl based upon his tastes and preferences. He remembers the full names of everyone receiving an 'A' rank, with Ryoko receiving an A++ and Nagato receiving an A−. As for Mikuru, her mere presence elicits an altered state of adoration for Taniguchi and Kunikida. He was Kyon's original source of information on Haruhi before he started conversing with her. He inadvertently lets slip that he is the person who dated Haruhi for the shortest time, five minutes, while she was in junior high. Kyon and Taniguchi share a typical teenage male friendship, openly deriding and being cruel to each other, with any animosity forgotten by the next time they meet.
- In The Melancholy of Haruhi-chan Suzumiya he usually gets the short end of the stick in the episodes that he appears in. This includes being on a scavenger hunt for so long that the game was over when he came back and becoming an "oni" when in fact all that Haruhi assigned for him was to sit still in "icy isolation".
- Kunikida (国木田)
- Voiced by: Megumi Matsumoto (Japanese); Brianne Siddall (English)
- Kunikida is a friend and classmate of Kyon. Kunikida is much quieter than Taniguchi with the latter doing most of the talking when the two are around. Kunikida plays a minor role and does not contribute much dialogue. Since he and Kyon went to the same junior high school, he is more familiar with him. He is smarter than his friends Taniguchi and Kyon, at one time explaining a difficult concept to Taniguchi. Kunikida is included in certain SOS Brigade activities when there is a shortage of people, such as the baseball game and the movie The Adventures of Mikuru Asahina.
- The Computer Research Society President (コンピュータ研究会部長, Konpyūta Kenkyūkai Buchō)
- Voiced by: Nobuyuki Kobushi (Japanese); Dave Wittenberg (English)
- He is the president of the Computer Research Society (or Computer Society), which shares a room adjacent to the SOS Brigade. The President is never given a name other than "Computer Society President" or variations upon that term (all that is known of his name is the first syllable: "ya"). He and his club are blackmailed into giving away their best computer and wiring the Brigade's clubroom for an internet connection. He later challenges the SOS Brigade to a rigged contest using the Computer Research Society's own basic science-fiction strategy game, The Day of Sagittarius III, betting four of his club's laptops in an attempt to reclaim the originally pilfered computer. Yuki counters the Research Society's cheating by reprogramming the code in-match, and the SOS Brigade wins. The President is impressed enough to ask Yuki to participate in his club's activities, which she agrees to.
- In "Mystérique Sign", he is trapped in an alternate spatial frame that was unknowingly triggered by Haruhi. He was, in turn, freed by the other members of the SOS Brigade.
- Emiri Kimidori (喜緑 江美里, Kimidori Emiri)
- Voiced by: Yuri Shiratori (Japanese); Hynden Walch (English)
- A soft-spoken, well-groomed second-year student with long, light green hair, Emiri first appears in "Mystérique Sign" seeking counsel from the SOS Brigade. Although she claims to be the girlfriend of the Computer Research Society President, Kyon later discovers that this is not the case, and that Emiri is a humanoid interface like Yuki and Ryoko. Emiri later becomes the secretary to the president of the Student Council. By this time, it is implied that she is Yuki's superior, or at the very least her minder, as a consequence of Yuki's world-altering actions. Emiri works part-time (against the rules of the School Council) as a waitress in the cafe frequented by the SOS Brigade.
- Student Council Chairman (生徒会長, Seitokaichō)
- A student hired by the Agency to play the part of the archetypal nemesis to Haruhi, as yet another attempt to relieve her boredom. He attacks the Brigade, on the grounds that it is not a legitimate club, using the school rules. When acting as Haruhi's nemesis, he wears glasses and acts cold and polite. When Haruhi is not present, he is easygoing and brash, removes his glasses, and sometimes smokes cigarettes. He has noted that he is growing accustomed to his role and that he enjoys wielding power. His name remains unknown.
ENOZ
ENOZ is an all-girl student band featured in "Live a Live" and its anime adaptation "Live Alive", though the band is not named in "Live a Live". The name derives from the last names of the members: Enomoto, Nakanishi, Okajima, and Zaizen. During the high school festival Enomoto (lead singer and guitarist) has tonsillitis and Nakanishi (guitar) suffers a sprained wrist, so Haruhi and Yuki fill in for the missing members. In "Live a Live", the band consists of only three members; the singer/guitarist was split into two characters for "Live Alive".
In "Live a Live" the impromptu band performs a full set, while in "Live Alive" they only perform two songs, "God Knows" and "Lost My Music", with Haruhi explaining that she and Yuki didn't have time to learn any more. The episode trims both songs down as inserts. "God Knows" has all of the song save for about half of the guitar solos during the beginning and end, and the entire second stanza and chorus. "Lost My Music" barely finishes the first stanza and chorus, leaving the second and third out.
"God knows" and "Lost My Music" were included in the soundtrack EP Suzumiya Haruhi no Tsumeawase (涼宮ハルヒの詰合 ~TVアニメ「涼宮ハルヒの憂鬱」劇中歌集シングル~). The sole vocals for ENOZ are sung by Japanese pop singer and voice actress Aya Hirano, who voices the main character of the series, Haruhi Suzumiya. In addition, Hirano sings the main opening and ending themes for the series. (See a listing of Haruhi Suzumiya albums.) Susumu Nishikawa (西川 進) plays the guitar, Takeshi Taneda (種子田 健) the bass, and Yutaka Odawara (小田原 豊) the drums. In the English version, the songs are performed by Wendee Lee, Haruhi's voice actress.
ENOZ is a homage to the real life all-girl J-pop band Zone. Its name is simply "Zone" spelled backwards.[5]
The members of ENOZ are:
- Miyuki Enomoto (榎本 美夕紀, Enomoto Miyuki)
- Voiced by: Mai Kadowaki (Japanese); Michelle Ruff (English)
- Is the lead singer and guitarist in the band (the Italia Mondial II Woody Deluxe Woodtop used by Haruhi is hers).
- Takako Nakanishi (中西 貴子, Nakanishi Takako)
- Voiced by: Ryoko Nagata (Japanese); Megan Hollingshead (English)
- Plays guitar in the band (the White Limited Edition 1966 Gibson SG used by Yuki is hers).
- Mizuki Okajima (岡島 瑞樹, Okajima Mizuki)
- Voiced by: Mina Hiroe (Japanese); Patricia Ja Lee (English)
- Plays drums in the band, shown to be a Pearl Drum set in the anime.
- Mai Zaizen (財前 舞, Zaizen Mai)
- Voiced by: Sara Nakayama (Japanese); Kari Wahlgren (English)
- Plays bass in the band (is shown using a green Fender Precision Bass).