In a familiar yet different universe, shy bookworm and gamer Yuki Nagato is the president of North High School's Literary Club. Her friends, the overly-cautious Ryouko Asakura and completely average Kyon, are the only other members of the club. Nevertheless, Yuki enjoys the peace and quiet she shares with them, especially when she is with Kyon, whom she has a crush on. Added to the mix are Tsuruya and Mikuru Asahina, two friends with opposite personalities who frequently stop by the Literary Club. While walking back to her apartment on a cold December day, Yuki is coerced into drawing strange symbols on the ground by a girl supposedly attempting to capture Santa Claus. The girl introduces herself as Haruhi Suzumiya, an eccentric student from the prestigious Kouyouen Academy who is on the hunt for aliens, time travelers, and espers. When Haruhi and her friend Itsuki Koizumi make a sudden appearance in the clubroom, they declare themselves as official members of the Literary Club, with Haruhi taking up residence as the executive president. With the tranquil days of the Literary Club now behind them, Yuki and her friends get caught up in a series of misadventures under Haruhi's leadership—with each incident bringing Yuki and Kyon closer than ever before.

Honda, Kawasaki, and Suzuki all comprise the elite ninth unit of the Sushi Police—a task force with the sole objective of sniffing out restaurants serving illicit or non-traditional sushi and eradicating them, no matter how insignificant their offense may be. The Sushi Police travel freely around the world in pursuit of these vile criminals day or night, with their strong sense of justice and the World Food-Culture Conservation Organization backing them. No offenders of Japan's traditional cuisine can escape their wrath! During one of their purification missions, the Sushi Police encounter Sara—a hot, young, television reporter out to expose them and the World Food-Culture Conservation Organization for corruption. They interrogate her, but her wiles, skills, and charms allow her to easily escape from their grasp, setting off a chain of events that will lead to the true purpose of the Sushi Police being revealed.