Agasa Hiroshi is an inventor and Shinichi's closest neighbor, living in a large house right next to the Kudou residence. He makes his living with a wide number of patents and inventions, mostly video games (of whom the Detective Boys are enthusiastic test players). He has been a friend of Shinichi and Ran since their childhood years. After Shinichi had been shrunk by the APTX 4869, the first person he met and entrusted himself to was Agasa. After having been convinced that the little boy was Shinichi, Agasa was also the first one to advise Shinichi to exercise caution in his pursuit of the Black Organization. He also helped Shinichi in establishing his new identity as Edogawa Conan, including constructing several gadgets which help Shinichi in carrying on his detective work surreptitiously, and in order to perfect Conan's cover, he also enlisted him into Teitan Elementary and thus came to know the children who would form the Detective Boys. When Miyano Shiho fled the clutches of the Black Organization, she fled to Shinichi's house but collapsed from exhaustion before Agasa's doorstep. Agasa subsequently took her in, learned about her true identity and helped her establish her new identity as Haibara Ai. He also entrusted Shinichi's parents with the secret about what has happened to their son. Ever since these beginnings, Agasa has been an invaluable friend for Shinichi and the Detective Boys as a confidant, paternal friend, and someone to hang out with. He often takes the children on trips, most of which turn into criminal cases instead. Agasa is a jovial and outgoing person and has many friends in his community, a fact which helped him in his covering up of Conan's and Haibara's true origins (he simply claims that they are the children of his friends and acquaintances). Agasa has a special love for pasta and tomato juice.
Lum's best childhood friend. She appears to be a sweet and lovely redhead, but in actuality has a violent split personality. Her special power is the ability to suck the vitality out of a person’s mouth while kissing them. She can also use this power in reverse. As a child, Ran was often hurt or got into trouble because of the antics of the more carefree and irresponsible Lum. Also, she is in love with Rei who unfortunately still loves Lum. For these reasons, she came to Earth in order to get revenge against her one-time friend. Ran is an excellent cook, always hoping against hope that the way to Rei's heart is through his stomach. Source: Wikipedia
One of Ataru's teachers. A sad, middle-aged man, whose only interest is to teach at Tomobiki High, but fails due to the constant interruptions during class, when the classroom itself is not destroyed by Lum, Ten or Shinobu. His name means "Mark of the Hot Springs", and he usually wears a shirt with hot springs on it.
The primary antagonist and Kamui's dear friend. Fuuma is initially kind and gentle. He helps his father dutifully and dotes upon his younger sister Kotori, and excels at high-school sports. After Nataku attacks Kyogo and steals the first Shinken, Fuuma's dying father tells him that he is Kamui's twin star. Accordingly, when Kamui chooses the Dragons of Heaven, Fuuma is forced to become a Dragon of Earth, immediately attacking Kamui. He proceeds to grant wishes to the characters with whom he interacts, in ways that often lead to their death or that of a loved one. Tsubasa: Reservoir ChronicleHe is Seishir�'s younger brother, a friend of Yuko Ichihara and de facto leader of the people of the Tower. In actuality, he's a treasure hunter who can travel across dimensions and often searches artifacts at Yuko's request. He is on friendly terms with the main characters in the series.
A dragon of Earth, Nataku is an androgynous clone of extreme psychic ability, born of genetic material of TÅ�jyÅ� Kazuki, the deceased granddaughter of the president of TÅ�jyÅ� Pharmaceuticals, and her father Masaki. It is sent to retrieve the Shinken by the Chairman TÅ�jyÅ� who wishes to destroy the sword so that Nataku cannot become entangled in the matter of the Promised Day. In the process of stealing the Shinken, Nataku mortally wounds KyÅ�go, FÅ«ma and Kotori's father, who was attempting to protect the Shinken. Nataku is haunted by the memories of its previous life as Kazuki, and follows FÅ«ma unquestionably as FÅ«ma resembles the person Kazuki cared most for—her father. In Tsubasa Reservoir Chronicle Nataku is one of the fighters of the City Hall faction. Unlike in X, he is a mentally developed adult and takes care of Kazuki, alternate version of X's Kazuki (who substitutes Seishirou's place)
Tokyo Babylon Seishirou is a kind veterinarian. He joins in with Hokuto in teasing Subaru about them getting married, but always laughs it off as Subaru blushes furiously. Seishirou is actually the Sakurazukamori (powerful assasin onmyouji), or the "Sakura Assassin" whose signature is cherry blossoms and the symbol of an inverted pentagram. He made a bet with Subaru long ago, which entails the climax of the series. X Seishirou is one of the Dragons of Earth, where he reveales his true self as a cold-hearted assassin who killed Subaru's twin sister Hokuto. In their final battle at Rainbow Bridge, Seishirou arranges for Subaru to kill him realizing who really won the bet. Tsubasa: Reservoir Chronicle A vampire hunter who chases after the vampire twins (Subaru and Kamui) across worlds. By exchanging his right eye, he received the power to cross dimensions from Yuuko Ichihara, the Witch of Dimensions. He was also the one who taught Syaoran how to fight.