It follows the story of Dr Kenzo Tenma, a leading neurosurgeon, as his life falls apart due to the sudden death of other hospital employees, and the disappearance of a special patient of his. He is suspected of the murders, and so must run from the law, whilst trying to hunt down the real killer. Said killer is a freaking awesome sociopath. CB

Nana Osaki is a punk singer who wants to debut with her band, Black Stones (BLAST for short), where she is the lead vocalist and her boyfriend, Ren, is the bassist. Nana and Ren have lived together as lovers since she was 16. When Ren is offered a chance to debut in Tokyo as a replacement member of the popular band, Trapnest (Toranesu in Japanese), Nana chooses to continue on with BLAST and to cultivate her own career instead of following Ren, as she has too much ambition to simply be a rockstar's girlfriend. She eventually leaves for Tokyo at the age of twenty to start her musical career.

Nana Komatsu, the other Nana, has a habit of falling in love at first sight all the time, and depending on other people to help her. When her friends, and then her boyfriend, leave for Tokyo, she decides to join them a year later after having saved enough money at the age of twenty.

The two Nanas meet on a train by chance, both on their way to Tokyo. After a string of coincidences, they come to live together in an apartment numbered 707 (nana means "seven" in Japanese). Despite having contrasting personalities and ideals, the Nanas respect each other and become close friends.

Nana Osaki gives Nana Komatsu the nickname Hachi (after Hachikō, because she is weak-willed and has characteristics that resemble a puppy, and also as a joke since hachi means "eight" and nana means "seven" in Japanese).

While BLAST begins to gain popularity at live gigs, the two Nanas face many other issues together, especially in the areas of friendship and romance. The story of Nana revolves heavily around the romance and relationships of the two characters as one seeks fame and recognition while the other seeks love and happiness.

Yukio, known by his friends as "Koyuki", is a regular 14-year-old Japanese boy who enters junior high school with two childhood acquaintances. One is a pervert, and ironically the other is a highly sought after female student. Koyuki's boring life is changed when he saves an odd-looking dog, named Beck, from some kids. Beck's owner turns out to be an emerging rock musician, Ryūsuke Minami, who soon influences Koyuki to start playing the guitar, and even gives one to him. The story focuses on the trials and tribulations of their rock band named BECK, and Koyuki's relationships with the members of the band, in particular Ryûsuke Minami and his sister, Maho Minami.

ES (Eternal Sabbath) is a gene developed by a group of scientists who sought immortality. The presence of the gene grants the carrier up to 200 years of life immune from all viruses. Though the scientists' original intention was to demonstrate the feasibility of eternal life, ES unexpectedly has the additional power of mind-control and memory-alteration.

A female neurology professor, Mine Kujo, meets a man by the name of Ryosuke Akiba and discovers that he is a genetically-engineered human with the ES gene. Together, they pursue a more dangerous ES-carrier who had escaped from the research center.

The series' plot focuses on Kimihiro Watanuki, a high school student plagued by yōkai and ayakashi, spirits with a strong attraction to him. The spirits are invisible to others and encounters with them are extremely troublesome. When he stumbles into a shop that grants wishes, however, events in his life promise to become more unusual. The shop is owned by Yūko Ichihara, a mysterious witch of many names and esoteric renown. For a price, she offers to grant Watanuki's wish to be rid of the spirits. The price, according to Yūko, must be of equal value and so, as payment, he temporarily becomes Yūko's part-time employee. Watanuki's job consists of small errands dealing with the supernatural and household chores. Himawari Kunogi, Watanuki's love interest, and Shizuka Dōmeki, a classmate who Watanuki detests, occasionally join him in his work as per Yūko's request. The three become increasingly close despite Watanuki's annoyance with Dōmeki. Although Watanuki becomes happy with the new friendships he makes, he becomes concerned about Yūko, promising he will try to grant her wish.