Taniguchi, a classmate and friend of Kyon at North High School originally assigned to Class 1-5, hails from the same junior high as Haruhi Suzumiya, positioning him as Kyon’s key informant about her past. With a reputation for flirtatious antics and a playful demeanor, he employs a personal ranking system to evaluate female classmates’ attractiveness, memorizing the full names of those scoring an "A" or higher. Notable entries include Ryoko Asakura’s AA+ and Yuki Nagato’s A- ratings. Despite his evaluative habits, he maintains strictly platonic relationships, avoiding romantic pursuit.

His shortest romantic endeavor—a five-minute "relationship" with Haruhi Suzumiya—remains a humorous footnote. He exhibits pronounced admiration for Mikuru Asahina, reacting with heightened enthusiasm to her costume changes while keeping his admiration distantly respectful. Frequently seen alongside Kunikida, Taniguchi participates peripherally in SOS Brigade activities as an auxiliary member, offering occasional support alongside figures like Tsuruya and Kyon’s sister.

In the alternate universe of *The Disappearance of Nagato Yuki-chan*, a botched attempt to attract girls at Kouyouen results in an accidental collision with Kuyoh Suoh. Escorting her to the infirmary sparks an unexpected romantic subplot, marking one of his rare direct narrative engagements.

Described as an average-height teenage male with ear-length black hair and brown eyes, Taniguchi pairs a talkative nature with reluctance to approach girls individually, often masking genuine interest with exaggerated bravado. Though secondary in the franchise, his presence delivers comic relief and exposition, particularly regarding Haruhi’s history.