Tomoe has long brown hair and seems to be a bit shorter than her brother Houtarou. Her eye color is somewhat greenish or could be the same colour as Houtarou. Her face is almost fully revealed and it was shown during the Kanya Festival when she's about to check how Houtarou's doing. She wears a variety of styles for casual clothes from simple tops and short pants at home to colorful attire when going out.
Tomoe's personality seems to be wild, active and ambitious who enjoys travelling that she has traveled alone across the continent of Eurasia at the time of her college enrollment, and even had the experience of climbing a 2000 m mountain. As a martial arts expert in Aikido and Taiho-jutsu  and a proficient university student, she "was not content with conquering Japan alone, and had decided to go out and challenge the world."
From the letters she wrote and the interactions she has with Houtarou Oreki (Tomoe's younger brother) at home that she is also a bit of a hasty and pushy individual. Whether or not this pushiness is something she also does to others is unknown.
Based on her interactions with Houtarou again, she can be a rather flaky and/or irresponsible individual at times, as shown when Houtarou asks for a good luck charm, she gives him a broken fountain pen.
While much is not known about Tomoe yet, she plays an important role in the series, often contributing to the circumstances Houtarou Oreki (Tomoe's younger brother) would face at school. By the start of Houtarou's second year in high school, Tomoe is in Benares in India, en route to Sarajevo in Bosnia and Herzegovina. In one of the letters she habitually sends to Houtarou, she told him to join the Classics Club. Although Houtarou is quite lazy and refuses to join, he eventually reconsiders because he knows that his sister "would make it very painful to refuse". Eventually, her letter would allow the Classics Club to form once more, and she intervenes once again, this time in a case involving the issue of the Hyouka anthologies of 45 years ago, when she mentions the location of old anthologies from the Classics Club.
Tomoe maintains contact with Houtarou by mail or by phone and later pushes Houtarou in a case involving the amateur film of Class 2-F for the Kamiyama High School Festival by referring him to the third year Fuyumi Irisu. She later warns Irisu about messing with Houtarou following the developments of the case.
Soon enough, she comes home, just in time for the day of the school festival. Tomoe even participates in the "Straw Millionaire" situation Houtarou found himself in, by giving Houtarou a fountain pen, and later trading Houtarou's hand mirror for a copy of "A Corpse at Night", which Houtarou later required to solve the Juumonji Incident.
Throughout the novel, she travels around the world, from New Delhi to Beirut and so on. Readers also learn that Tomoe asked her little brother to join the Classics Club because she was a member in the past. It seems that she has a connection with Jun Sekitani because, in a brief phone conversation, she is able to give Houtarou a clue about the uprising Jun was connected to 45 years ago.
Houtarou is Tomoe's younger brother whom she has a warm family love for him, even though Houtarou himself is not fond of it and normally acts more bored, in a possible attempt to ignore her. However, he seems to fear her in other ways, such as knowing that he'd face "something painful" if he tried rejecting Tomoe's request of joining the Classics club.
Due to being able to give some hints to Jun Sekitani's connection to the events of 45 years ago, Tomoe may have possibly been an acquaintance.
- The name Tomoe means "companion" (供) (tomo) and "favor, benefit" (恵) (e).
- Tomoe's surname Oreki means "occasion" (折) (ore) and "tree, wood" (木) (ki).
- In the Kanya Festival, Eru Chitanda and Tomoe share eye contact in the hallway, with Chitanda following with: "I feel like if I've seen that look before.", which may be a hint that Tomoe's eyes resemble Houtarou Oreki's eyes.
- In "Credit Roll of Fools", Houtarou mentioned that the book about Tarot Cards from his bookcase belongs to his sister. Since Tomoe was part of the Classics Club, most of the books probably belongs to her but she left her bookcase to her brother.
- It is also hinted that she may have connections with the other characters in the anime, unknown to Houtarou. Like Fuyumi Irisu, based on their chat as she called Houtarou as "the idiot".
- It's worth noting that Tomoe and Houtarou are based on Sherlock and Mycroft Holmes with interchanged traits.
- In most aspects, Tomoe is much like Sherlock, being adventurous on top of being knowledgeable in martial arts or self-defence. Houtarou on the other hand is like Mycroft, someone who didn't indulge in mystery-solving (neither being that adventurous) and not being that athletic.
- However, as seen in the series, Houtarou has exceptional deductive skills, to a similar level of Sherlock. He also has the "sidekick," who is Chitanda. While Tomoe does not show up to offer any signs of deductive reasoning, it is implied that she too is smart, but not as much as Houtarou, which is a case similar to Mycroft. She also lacks an apparent sidekick.
- This is a very apparent reference to Sherlock Holmes, as the series is referenced a number of times within the whole series.
|Classic Literature Club series and Hyouka Featured Characters|