Madoka Ayukawa
The archetypical "kimagure" (whimsical) character, Madoka is secretly in love with Kyōsuke, and is best friends with Hikaru Hiyama (who is also in love with Kyōsuke). Madoka is described as having an adult allure despite being in junior high school.
When she first meets Kyōsuke, she appears to be a pretty and sweet girl. This, however, is in stark contrast to her personality at school, where she is aloof and feared by both the male and female students as a reputed juvenile delinquent. In the TV series she is nicknamed "Madoka the Pick" due to her ability to wield a guitar pick like a shuriken. Despite her "punk" reputation, Madoka is also shown to excel at various activities both scholarly and athletic. She is able to earn high marks in school and still work a part time at Cafe ABCB (pronounced "ah-ba kah-ba").
Madoka's parents are kind-hearted but workaholic professional musicians often touring outside Japan, so she lives in a large house with her older sister. After her sister gets married and goes to live abroad with her husband, Madoka lives there alone. The story involves the eventual shedding of her tough exterior after she becomes Kyōsuke's friend, as evidenced by the changes in her life after she meets him. She gives up smoking because of him, and in the manga other characters note that she becomes friendlier and does better academically following Kyōsuke's arrival.
As revealed in the last episode of the anime (which occurred near the end of the manga run), Madoka also holds a special place in her heart for a mysterious man whom she met under a tree in the past. Madoka drastically changed her appearance starting 6 years ago after her encounter with present-day time travelling Kyosuke, who in fact was stating his preferences based on the present-day Madoka. In the end, Madoka still did not know that Kyosuke was the mysterious man, but senses a connection to him.
Creator Izumi Matsumoto reports that his inspiration for Madoka was actress Phoebe Cates.

Hikaru Hiyama
Hikaru is initially presented as being unpleasant, a brawler, and a tougher talker than Madoka. But once she becomes friends with Kyōsuke, it is revealed that she is actually very kind and energetic. She accidentally sees Kyōsuke perform an impressive basketball shot using "The Power" (it was not obvious that The Power was used), and ends up falling for him quite hard. She always refers to him by the English word "Darling" (even before she knew his name). Hikaru tends to revert to a form of baby talk, which is a signal she is extremely immature and shielded. She has an unrequited love for Kyōsuke, and has been Madoka's best friend for several years since she and Yūsaku Hino were the only ones who were never afraid of her. Hikaru is two years younger than Maodka and Kyōsuke, and has the same birthday as Kyōsuke.

Manami Kasuga
One of Kyōsuke's younger sisters, Manami is very reserved. She is depicted as the homemaker of the house?cooking meals, vacuuming and doing laundry?but it is revealed in both the manga and anime that she has a wild side that occasionally needs release. Manami's esper powers include teleportation and telekinesis. Part of her reserved nature includes avoiding excessive use of The Power unless it is absolutely necessary.
In the manga she is especially fond of Madoka and would like to see Kyōsuke and her get together. However this never made it into the anime. As such the anime version shows no such preference, though she and Kurumi at times urge Kyōsuke to choose between Madoka and Hikaru. But even in the manga she is unaware of the situation between Kyōsuke and Madoka.

Kurumi Kasuga
Manami's fraternal younger twin, Kurumi is very energetic and argumentative. She is also able to bring these qualities out in Manami as well. She is known to use idioms of her own creation, which can sometimes be misconstrued by others. Kurumi is the most comfortable with using her powers, often doing so without thinking about the consequences. Kurumi used "The Power" to run the 100-meter dash in 3 seconds at her old school, which resulted in the Kasugas moving to the town where the series takes place. Kurumi's other esper powers include teleportation and telekinesis. She also possesses the ability to hypnotize, and Kyōsuke is her usual victim. Although Kurumi appeared to learn this from a book, her actual ability is probably derived from "The Power".
In the manga Kurumi wants Kyōsuke to end up with Hikaru. But, again, this storyline never made it into the anime, and the anime Kurumi shows no such preference.

Takashi Kasuga
Kyōsuke's father, he works as a photographer and has no esper powers.

Akemi Kasuga
Kyōsuke and the twins' mother and Takashi Kasuga's wife, she died after giving birth to the twins. The Kasugas' powers come from her side of the family; since Akemi was the Kasuga's only daughter (apparently Akane and Kazuya are the children of her cousins), her husband married into the family so their Kasuga surname survived. After the grandparents asked Takashi for a almost impossible task in the mountains to accept him fully, she secretly used "The Power" to help him win their hearts.

Master
Proprietor of the ABCB cafe located on Orange Road and Madoka's boss. He is one of the few characters who realizes how Madoka and Kyōsuke feel about each other, and does everything in his power to smooth relations between the two. In the manga he shuts down ABCB after it is discovered that Kyōsuke was working there (at the time of the story, Japanese high school students could not hold jobs). In the novels it is revealed that he bounced back by opening one of the first cybercafes in Tokyo.

Seiji Komatsu
Naoki Tatsuta
Kyōsuke's two bumbling sex-obsessed friends. They are also potential boyfriends for the twins, who are most likely using them as placeholders until someone better comes along. Kazuya Hatta is not to be confused with Kazuya Kasuga. Komatsu's first name has also been given as Masashi (most notably in the credits for "An Unexpected Situation"). In the novels, Hatta becomes an aspiring manga author, and Kazuya gets trapped inside of one of his stories and Kyōsuke has to bail him out. By the time of the second film, they have achieved some success publishing girlie magazines.

Kazuya Kasuga
Kyōsuke's younger cousin, Kazuya looks like a younger version of him. On several occasions people have mistaken Kazuya being Kyōsuke's son. Kazuya has "The Power" as well. In both the manga and the anime he uses telepathy almost exclusively, with telekinesis being used on very rare occasions. Kyōsuke and Kazuya can swap bodies by banging their heads together, and many stories with Kazuya involve him doing so either to avoid something unpleasant, or to "help" Kyōsuke pick which female to focus on. In the manga Kazuya has two female friends, and his situation with them somewhat mirrors the situation between Kyōsuke, Madoka, and Hikaru.

Akane Kasuga
Kazuya's older sister, and the same age as her cousin Kyōsuke. She is rather tomboyish, and both Komatsu and Hatta are intimidated by her. Akane can use "The Power" to make people see illusions. She has only been seen using this power to make herself appear as different people; it is unknown if she can create other types of illusions. The illusions appear to be both aural and visual. In the manga, this power works only on the person it is directed towards, so it is probably a mixture of telepathy and hypnosis, elements of "The Power" which have been demonstrated in other members of the Kasuga family. In the anime she uses it on both Hatta and Komatsu at the same time.
In the anime Akane has the same powers that Kyōsuke and the twins have, in addition to her illusion power. It is never indicated if this is true in the manga.
Akane's appearance in the manga and anime are quite different. In the manga she looks like a cross between Kurumi and Manami. In the anime her hair is shorter and darker, her face is more stark, and she has violet eyes. Akane only appeared in two of the OVAs (where she is shown to be rather infatuated with Madoka), and never in the TV series. She appears considerably more often in the manga, almost being a regular.

Yūsaku
Yūsaku initially appeared early in the series as a potential rival of Kyōsuke for Hikaru's affections, having harbored feelings for her since childhood. He asked her to marry him one day and she jokingly said she would if he became stronger and self assured. This sent him on the path of practicing karate for years. He views Kyōsuke as a womanizer on top of being a rival for Hikaru's love. Unfortunately for his romantic situation, he tends to get nervous and unable to speak in Hikaru's presence. As a result, she is unaware of his feelings and nothing happens between the two of them.

Sayuri Hirose
Sayuri is an extremely cute girl who only appears in the manga, and whose seemingly innocent and pure demeanor hides a devious mind obsessed with breaking as many male hearts as possible. She carries a book where she tracks the various males that she has left heartbroken. At her first meeting with Kyōsuke, he leaves her to walk to class with Madoka. Because of this she becomes obsessed with both of them, and comes up with various schemes to wreck their relationship. Most of her schemes involve bragging to Madoka that she's going to steal Kyōsuke, and then playing the role of the damsel in distress toward the kindhearted Kyōsuke. Fortunately, the schemes invariably backfire?often quite spectacularly.
Because she first saw Kyōsuke with Madoka, Sayuri assumes that the two are dating. Although Sayuri sees Kyōsuke on one occasion with Hikaru, there is no indication that she ever realizes that Hikaru is the one publicly acknowledged as Kyōsuke's girlfriend. This makes her pivotal in the manga, as she is the one who tells Hikaru about the relationship between Kyōsuke and Madoka, forcing the events that occur at the end of the manga.

Hiromi
Hiromi only appeared in the manga. She was Kyōsuke's classmate at his previous school, and transferred to Kōryō about halfway through the manga's run. She enjoys messing with Kyōsuke's head, and neither the reader nor Kyōsuke is sure if Hiromi knows about "The Power".

Ushiko and Umao
Ushiko and Umao are a newlywed couple that serve as one of the primary running gags in the TV series. Their appearance in an episode generally consists of them saying the same romantic lines to one another, followed by a chaotic event involving Kyōsuke or other primary characters, sometimes in the most ludicrous places. In the movie Kimagure Orange Road: I Want to Return to that Day, their appearance is limited to Umao, who appears on television holding a crying baby and begging for Ushiko to return to him.
Ushiko and Umao's names are references to farm animals. "Ushi" is the Japanese word for "cow," and "uma" means "horse."

Jingoro
Jingoro is the Kasugas' pet cat in the anime. He does not appear in the manga. Jingoro gets his name from the Edo-period wood sculptor Hidari Jingorō, who is thought to have carved the famous Sleeping Cat sculpture at the Nikkō Tōshō-gū. Jingoro is often the victim of Manami and Kurumi's abuse of "The Power." Because of this, he often attempts to flee the Kasuga household.