Black Stones, or Blast (Burasuto) for short, plays punk music. Once, they were playing with Honjou Ren; after his departure to join Trapnest, a new member, Okazaki Shin, joins the band. They attract a large audience and their ability is affirmed by a record company (Gaia). They are currently preparing for their debut.
About NANA: Osaki Nana is a punk singer who wants to debut as soon as possible to leave her ex-boyfriend, Honjou Ren, behind. Nana and Ren were in the same group once, but Ren was offered a chance to debut in Tokyo as a replacement member of Trapnest, a popular band. Nana had to choose between either going with Ren and being a groupie with the band, or staying with her own band. Realizing that following Ren would mean giving up her own dream to be a singer, she chose to cultivate her own band, Black Stones or BLAST for short.
Komatsu Nana, the other Nana, is called Hachi (Hachikou) by everyone in the manga after she met Nana(as explained in the manga, to avoid confusion of their names). Nana described Hachi as a little puppy, very loving to other people but demanding so much attention. ("Hachi-ko" is the name of a famous dog in Japan. Coincidentally, "hachi" is a homophone for "eight" in Japanese.) She grew up in a sheltered suburban lifestyle in which she was treated as a child for much of her life. With a habit of falling in love at first sight, Hachi has always depended on other people to help her, especially her high school friend Saotome Junko. However, Junko eventually had to leave Hachi to attend a selective art design college in Tokyo. Hachi desperately wanted to follow Junko to Tokyo, but had no means in which to support herself there. However, after working hard on her own, she was finally able to move there as well. Nana had a boyfriend at that time, called Endo Shouji.
Nana and Hachi meet in a train by chance and, after a string of coincidences having to do with the number seven, decide to live together in an apartment numbered 707 ("nana" is a homophone for "seven" in Japanese). Despite having contrasting characters and ideals, both Nanas like and respect each other. While the Black Stones begin to gain popularity at live gigs, other issues need resolving. After discovering the past story of Ren and Nana, Hachi invites Nana to the Trapnest concert in the hope that the couple will reunite. Nana accepts the invitation, but she goes with the determination of tying up her feelings for Ren once and for all. However, things go a little differently, and with some help from their mutual friend Yasu, Ren and Nana get back together. Though Nana's romance with Ren has been rekindled, Hachi's own lovelife is in shambles. She discovers that Shouji has been cheating on her with Sachiko, one of his coworkers. Hachi ends their relationship, saying that she never wants to see Shouji again.
Nana introduces Hachi to Ichinose Takumi, her favorite member of Ren's band, Trapnest. The two begin a romantic relationship, though it isn't an ideal romance. Hachi only sees Takumi when he has time off from touring and doing work for Trapnest. It seems to be purely physical, with Hachi aware of the fact that she doesn't really know Takumi as anything other than an iconic guitarist, and that he is notorious as a ladies' man. At the same time, the guitarist of Black Stones, Terashima Nobu, declares his love for her. Hachi is torn between her love for Nobu and her relationship with Takumi. In the end she chooses Nobu, and splits up with Takumi over the phone - although Takumi doesn't realize it. For a while Hachi and Nobu enjoy a happy, loving relationship - they understand each other and have fun together. Then Hachi finds out she's pregnant. Unable to bring herself to abort the baby and knowing that it must be Takumi's, she becomes listless and unhappy. Takumi returns, makes the discovery, and challenges Nobu - he'll take care of Hachi and the baby no matter who turns out to be the father. Hachi, thinking of her child's future, knows that while she loves Nobu he can't support her. When Takumi offers to marry her, she accepts. Hachi leaves the apartment she shares with Nana and she regrets it, but she can't bring herself to say it directly. Nana is also unable to express her feelings about the separation, though a marriage proposal from Ren offers hope for the future. Though the two friends are far apart, their thoughts remain with each other.
