Koto (translates to "Little Rabbit") is a demon girl that has been seen to be acting as the referee/commentator for both the Dark Tournament and the Demon World Tournament. She is later replaced by Juri as referee in both the semi-finals and the finals of the Dark Tournament, switching to mere commentary as she was suspected of miscounting in the match between Jin and Yusuke. She is also something of an idol in both the Human and Demon Worlds.
Koto is voiced by Ai Orikasa in the Japanese version and Amber Cotton in the English dub.
In the original Japanese, Koto is a bright and cheerful young lady who is admirably professional and devoted to her job, and is basically a good person who just happens to work for bad people. The English dub however, displays her as a vicious sadist, often giving her own commentary on how much she enjoys the pain and death she sees. In both versions, she has some standards as she disapproves of Bakken's attempts to keep Kurama's unconscious body in the ring.
Koto often seems overtly-amused in the suffering of the fighters at the Dark Tournament, but only when both contestants can fight, though she becomes easily frightened whenever there is a formidable attack such as the Dragon of the Darkness Flame, though not as much as Juri. In the Makai Tournament, this sadism is toned down a bit.
She also has the entire tournament rule book memorized, and points that out to Botan, during Jin's fight with Yusuke- Botan complained that Jin's fighting was an unintentional ring-out.
Koto is briefy the object of affection for Chu, whom she doesn't share feelings for. Ironically, in the Makai Tournament, she seems upset over the fact that Chu fell for Natsume. She sometimes puts on a cute act, but is very shrewd and manages to get in jabs at Juri being a former cocktail waitress.
In the manga epilogue, Ruka, Juri and herself have begun to really break out into Human World culture. She briefly appears in an ad in the Eizou Hakusho OVA. Koto admits to having a crush on an aloof, serious man, referring to Toya, who sneezes. However, in the anime, she also got infatuated with Yoko (not knowing that it was Kurama in his previous form caused by Ura Urashima's Idunn Box) when she sees him after Shishiwakamaru threw his sword to break Ura Urashima's barrier. She referred Yoko as her personal fantasy and a love god with sexy ears and a dreamy tail, though she gets over it a year later.
- The Funimation dub, in which Yusuke refers to Koto as a "fox girl", and her tail and ears resembling a fox cause most to believe Koto is a fox spirit. Some claim she may be a cat demon—she frequently meows in the manga, and in the Funimation dubbed anime she refers to her ears as "little cat ears" and is called a "kitten" by Bakken.
- Likely furthering the Australian stereotype, Chu calls her Sheila, as he does every other girl, which she seems to take a disliking to.
Chu: Chu was intially attracted to Koto because of her beauty, but when he found that out she could speak "drunk", his affection strengthened and persisted. Chu had also helped in saving her life when Toguro had begun draining souls from demons in the audience. By the Makai Tournament, his feelings had lingered, as indicated by his declaration of love for her. However, he eventually fell for Natsume, indicating that his former feelings for Koto were merely the result of a shallow infatuation. Koto wasn't interested in Chu, but was frustrated when he begged Natsume to be his girlfriend, screaming that, "he turned her bloody tournament into a dating service," possibly hinting at implicit feelings.
Jorge When Jorge decides to be announcer, he makes his way near her, in an unheralded manner, and proceeds to ask her useless questions and make useless calls, in both tournaments. Koto seems to not mind this intrusion- only noticeably annoyed when Jorge does something excessively stupid and superfluous. She remembers him as the "rapping ogre" in the English dub.
Juri: It is implied that Koto and Juri are good friends, and that Koto was the one who found her and got her into referee status- Koto was a star in the makai, after all. During their commentary, she frequently makes remarks seeming like she's guiding Juri on otherwise tough calls- Juri is a new referee, after all. And then there's what Juri said as the Dark Tournament dome stadium was collapsing...
Yusuke: Koto treats Yusuke like everybody else until the call with Jin, where Yusuke mistakenly threatens her, thinking she's involved with tournament committee calls, because though he'd won, they called a draw. Koto lets this go, but when Yusuke defends her against Risho, she seems to gain respect for him. This respect carries all over into the Makai Tournament, in which she addresses him as "Mister".
Botan: In the English version, where Koto was turned into a sadist, Botan was secretly disgusted at Koto's sadism. She also thought Koto was too into the fighting action to care about referreing. When she confronted the demon about her apparent disregard for the rules -in this case, not counting Jin out when he was flying over the ring- Koto proved Botan's ignorance by quoting a section of the official rulebook. Later, against Team Ichigaki, Botan was clearly disgusted at the sadism and called her a "heartless wreck." Although she didn't know it, Botan's insult had a profound effect- despite Koto still being into the violence in fighting, she started to show some standards, and when things got too brutal and unfair, she stood up for the weaker fighter. Naturally, this only happened to Team Urameshi, because the other fodder teams were easily destroyed by the ones who advanced, while Yusuke's team could hold out...and naturally, she got a lot of flak for this.
Toya: In the manga, Koto admit to having a crush on Toya, describing "He looks really [?] and hard to approach" and later she said she decided "He's gotta be really sweet on the inside." After Koto, Juri, and Ruka admit their crushes, without revealing names, the next page reveals Toya, Jin, and Susuka sneezing in unison, indicating that the female trio were referring to the men as their crushes.
Manga chapter: 173; p. 9 and 10