Tsuruya's Challenge is a Haruhi Suzumiya novella that first appeared in the light novel The Intuition of Haruhi Suzumiya. In the same vein as "Where Did the Cat Go?" and "Seven Wonders Overtime", it is strictly a puzzle game story; there is no true conflict, and the novella consists entirely of the characters trying to solve a puzzle that another character has challenged them with for fun.
During a meeting of the SOS Brigade, Itsuki Koizumi, Yuki Nagato, and visitor T discuss mystery fiction, and in particular the mechanic of a challenge to the reader. Due to a Beautification Committee meeting, Haruhi Suzumiya arrives to the SOS Brigade meeting late, and finds an e-mail to the SOS Brigade's e-mail account from Tsuruya, who her friend Mikuru Asahina says is away from school on family business. The e-mail issues a challenge to the SOS Brigade, with Tsuruya saying she stumbled upon a mystery during her trip.
The challenge takes the form of three attached documents, each containing a story. All three stories are first-person accounts from Tsuruya's family business trips and have a running theme of Tsuruya being bored with the enforced socializing on these trips and wanting to escape her familial responsibilities, with her family planting GPS trackers on her to keep her from absconding. None of the stories are conventional mysteries; instead, each has a narrative trick which the SOS Brigade must identify and unravel. The SOS Brigade refers to the three stories as "Episodes 1, 2, and 3", and Haruhi reads each of them aloud, imitating the characters' voices and Tsuruya's narrative voice.
- Episode 1
- At a party at a hotel, Tsuruya meets a girl her age and the two of them hang out. Wanting to escape the social expectations of their parents, they play tennis in their fancy gowns, change into tennis uniforms before heading back to the hotel, plant the girl's GPS tracker on a stranger, and hide under the bed in Tsuruya's room.
- Narrative trick: The e-mail and the writing style in the story itself imply this was a recent trip. In actuality, it happened seven years ago. Koizumi deduces this from the childish behavior of the characters.
- Episode 2
- Tsuruya and the girl from Episode 1 have continued to bump into each other on family trips, and become close. On a trip from this past fall, they bathe at a hot springs with the girl's "minder", assigned to chaperone her. On the drive back to the hotel, they stop at a local festival and participate in the grape-stomping contest. They then take the car to a station and board a train.
- Narrative trick: For most of the story Tsuruya's dialogue is summarized in the narrative (like Kyon's throughout the series), but towards the end it is quoted instead. This, in conjunction with her formal manner of addressing the girl, creates the deception that it is the minder speaking instead of Tsuruya, concealing the fact that the girls slipped away from the male minder when they got changed after grape-stomping. Haruhi and Mikuru catch on after they question why the girls were taking a train ride back from a hotel that was just a car ride away.
- Episode 3
- At another party, Tsuruya and a friend, Shouko, talk with a doctor who is courting Shouko. Shortly after he excuses himself, Tsuruya hears a shriek and finds the doctor lying on the floor with blood coming from his head. He whispers, "Don't swallow... Do not ingest..." The SOS Brigade are challenged to determine the culprit's name.
- Narrative trick: The language the characters are speaking is never indicated. Clues in the story lead Haruhi and Koizumi to realize that the story is set in a country other than Japan, suggesting that the doctor is not Japanese and was speaking in English. This allows them to deduce that the culprit's name, when written in Japanese order (i.e. family name first), forms a pun with the English phrase "Not to be taken orally": Notobe Takenao.
Tsuruya sends her follow-up e-mails within moments of the SOS Brigade solving Episodes 1 and 2. Kyon is bothered by this perfect timing, and Nagato directs him to look at T. He realizes that T's hairpin is actually a bug, and that T was visiting the clubroom so that Tsuruya could monitor the SOS Brigade's progress and send the e-mails out at the right times. He also deduces that T is the unnamed girl from Episodes 1 and 2, since the uncharacteristically formal tone of Tsuruya's dialogue suggests that she may have been speaking in a language that she is not fluent in - specifically, English. This implies that the girl was not Japanese, and while that only mildly narrows down her identity, metafictional analysis would mean that the girl has to be someone the SOS Brigade knows.
Haruhi decides that Tsuruya running into a real mystery is too unlikely to happen in real life, and that the isolation of the doctor, the culprit, and Tsuruya from the rest of the party is improbable at best. She concludes that episode 3 is largely fictitious and that the challenge was conceived by the Mystery Research Club, not Tsuruya. T confirms most of her suspicions but maintains that episodes 1 and 2 are only slightly embellished accounts of things which really happened to her and Tsuruya, and that while the events of episode 3 are fictional, the people in them are real. T also reveals that the challenge is a first draft for a game the Mystery Club is preparing for the Cultural Festival. Haruhi calls Tsuruya back and reveals she has intuited that Tsuruya has in fact already returned from her trip, explaining why she was able to send out all the e-mails without trouble. The cat out of the bag, Tsuruya enters the clubroom and hands out cookies.
Reflecting on the fact that Haruhi made an incorrect guess at what the narrative trick to episode 1 is, Koizumi says he fears that Haruhi's powers are now acting on her subconscious desires rather than by wishes she voices aloud (despite the fact that Koizumi has always said that Haruhi's powers are controlled by her subconscious desires, and all of her demonstrated uses of her powers have been consistent with this). T thanks everyone for helping test out the Mystery Club's challenge and calls them her friends.