When Nana was only four years old her mother Misuzu Osaki walked out on her leaving Nana to her grandmother. This was the last time Nana ever saw her mother and has forgotten what she looks like. Nana's grandmother was a very strict and careful elder, she refused to let Nana wear the colors pink and red because she didn't want Nana O. to turn men on like her mother did.
During high school Nana become a punk rebel once she met Nobu Terashima who introduced her to old punk and rock music such as the Sex Pistols. Sometime later she was accused of prostitution and was expelled from her high school when she didn't try to plead innocent .As her grandmother was getting older she died from an unknown fatal illness Nana believed her decisions are what killed her grandmother. During the winter of when she died Nana bought herself a red dress as she wasn't permitted to wear the color before along with pink.
Nana wore this red dress when Nobu took her to a punk concert. this is where Nana first met her boyfriend Ren Honjo. It was practically love at first sight as Nana was smitten over him during the whole concert she only had her eyes on Ren.
After this night Nobu, Yasu, and Ren were planning on making their own punk band and wanted a female singer to attract more record sales and fans. Ren offered Nana to join the band as their lead singer of Black Stones. Right away this became one of the most popular bands in Japan as there was a quick cult following. Many people liked Nana's punk Vivienne Westwood style, Nana eventually got a tattoo of a lotus which in Japan means Ren. The two lovebirds moved in together and lived a happy life until Ren told her that he was offered a big record deal from Blast to play with the band Trapnest in Tokyo. Even though Ren and Nana still loved each other they didn't want to go through a long distance relationship as they saw no point in it so from here the relationship ended.
To get her mind off of Ren Nana decided to follow her dreams to become a successful singer, Nana moved to Tokyo and re-formed Blast with Nobu, Yasu, and their new bassist member Shin. During the train ride to Tokyo Nana met a girl named Nana Komatsu , a sweet girl who can't make up her mind yet has big dreams like Nana O. The two Nana's decided to get an apartment (numbered 707 and Nana is the Japanese word for seven) together so they could split the bills despite their different personalities the two girls became best friends over time. So the girls wouldn't get confused with their names Nana O. gave Nana K. the nickname "Hachi" which is the number eight in Japanese and the name of the famous dog from Tokyo. Nana O. began to have a maternal side when it comes to Hachi especially if anyone would try to steal Nana K. from Nana O. Nana went so far that she even threatened Hachi's boyfriend Shoji who cheated on Hachi.
Overtime, Hachi realized Nana was the lead singer of the band Black Stones who was dating Ren.Hachi decided to take Nana to a Trapnest concert hoping to reunite Ren and Nana together. At first,Nana refused to go but to get Hachi off of her back Nana eventually caved in. For the first time in two years, Nana and Ren locked eyes on each other at the concert and on that night they showed their love to one another. To thank Hachi Nana introduced her to the Trapnest's bassist, Takumi, whom Hachi was starstruck over.Takumi was a very heartless person who slept with different women everyday, this made Nana wonder if he was suitable for her friend Hachi.
It became obvious that during the two years Nana and Ren were seperated for that they grew somewhat apart despite that they still love each other. Before Ren moved to Tokyo the two would share deep dark secrets and talk to one another but Nana lost some of her trust in Ren. Instead Nana confides in Yasu (who's like a father figure to Nana) whenever she has a problem. The reason to this is that Nana has a grudge for Ren abandoning her just like how Nana's mother left her when she was young.
Eventually, Blast gets a record deal at Gaia Records and quickly becomes popular overnight. This leads to paparazzi following the band around, rumors about Ren having affairs, and reveals the location of Nana's mother. To comfort Nana about the romance rumors Ren proposes to her and asks her to move in, Nana has agreed to this yet she still questions herself about the relationship. During this period of time, Nana feels she's losing Hachi to her husband Takumi as Hachi chooses him over her. Nana holds a grudge on the band Trapnest since Ren abandoned her for their band and the fact Ren admires the lead singer Reira. Nana hopes to reconnect with Hachi as the two girls are practically like sisters that share a bond with the apartment 707.
Sometime later, the two girls see each other at Reira's Birthday party after Hachi reveals she's engage to Takumi which Nana isn't too thrilled about. A company magazine named Search confirms Nana's mother is alive and her location is exposed to the public audience. It ends up Nana's mother has a a child named Misato Uehara who the band knows as Mai Tsuzuki, Hachi's friend.
Later on, Blast is unable to play concerts due to Shin and Ryouko being found with marijuana in possession and gets arrested. Gaia offers Nana a solo contract for the time being as Blast will be on hiatus waiting for Shin to come out of jail. Ren tried to quit his addiction of drugs to make Nana happy so she wouldn't leave him. Towards later chapters Ren is driving looking around for Reira to have a band meeting with Trapnest before Nana's birthday party. While on drugs he mistakes a cat for Nana and crashes his car resulting into a tragic death that made a major impact on Nana.
While Nana is preparing for her solo career Yasu delivers her the news that Ren is dead and the funeral will be in town. Nana attends the funeral but doesn't shed a tear as she's still stunned she lost her other half. After his death, Nana starts having panic attacks causing her to have breathing problems.
Nana decides to leave Tokyo as it reminds her of the past so she moves to England and dyes her hair blonde. Her current job is being a singer at a underground pub. Though most of the public believe Nana is dead except for Blast once they received pictures of Nana wearing a red dress showing her shoulder with the lotus tattoo singing. Hachi wants to go looking for Nana so they could be reunited again.