She is known for her hard work and dedication when it comes to her nation. She is virtually 'flawless' despite secretly being an anime and cosplay otaku along with her tsundere tendencies.
While competition-oriented either way, as Black Heart her personality doesn't change too much; the only real thing changing is her becoming even more competitive than before.
Noire is a girl who looks in her mid-to-late teens, with a slender figure, red eyes, and long black hair. Her hair is kept tied into two pigtails with blue ribbons, and go down to her waist. Her fringe isn't kept parted and she has two bangs that go down to her chin. Her attire consists of a maid-like black top with golden trimmings and white frills around her upper arm and chest, and also reveals a certain portion of her cleavage. Her skirt is white with black trimming and is rather frilled compared to her top, and goes down to her lower-thigh.
Noire, in a word, is tsundere. She is a girl who thinks highly of herself and strives to be number one in everything she does. Noire often does and say things but tries to play it off as if there is no more meaning behind her actions. It is possible that she is a very caring person at heart but masks it with snobby, arrogant attitude in the hopes people will not see through her facade. Despite her seemingly-elitist attitude, she's in all actuality quite sweet and caring once you get past her tsundere side.
As Black Heart, her eyes are cyan and her hair is pure white, and goes down below her shoulders somewhat, with her fringe standing above her eyes and bangs caressing her face. Her suit is black and white in color and the mechanical appearance is much more visible. It also exposes a mild amount of her cleavage. Her sleeves are pure black, with silver patches in the bicep and tricep area, her gauntlets are black with silver protrusions on the knuckle.
Black Heart's personality remains fairly unchanged in her goddess form. The only difference is that she becomes more aggressive and competitive than before, but other than that, she's basically the same.
The Goddess (Neptune) of Planeptune
Noire first appears in her transformation, Black Heart where she signs the friendship treaty disallowing the use of military force to gain Shares. When the speech was praised, she notes that Histoire must have been the one to write it not Neptune. A month later Neptune arrives in Lastation to learn how to be a better CPU. Noire refuses at first but after some teasing about Noire's lack of friends, she agrees to help Neptune. Uni then arrives to hand in paper work which Noire praises her for working at a normal speed. Noire allows Neptune some simple paper work which does not work out. Noire takes Neptune out on monster extermination.
When they run into some villagers, Noire transforms into her HDD form, Black Heart to show off. The villagers say that Dogoos are causing trouble. They find a field of Dogoos in Nasuume Highlands and Neptune attacks them to be overwhelmed by their sheer numbers. Nepgear, Compa and IF helps out and the Dogoos are taken care of. Black Heart berates Neptune since she is not taking it seriously enough to use her HDD form. Black Heart goes to hunt the remaining monsters in Torunne Cave.
Black Heart heads into Torunne cave to find an Ancient Dragon. She fights it and has the upper hand until a monster knocks Black Heart into a strange red crystal which reverts her back to Noire. The dragon attacks Noire and in Neptune her HDD form, Purple Heart intercepts the dragon. She mocks Noire saying that she should be in her HDD form and is not taking the fight seriously. Purple Heart fights the dragon. Noire kills the monster that knocked her into the red crystal before it could do the same to Purple Heart. Purple Heart then kills the dragon.
Noire is then thanked by the villagers and Purple Heart who notes that the location of the quest was between Planeptune and Lastation further increasing the shares of Planeptune and legitimacy of the friendship treaty. Noire is happy but wonders what happen inside the cave and why did her transformation cease?
The Terrorist (Lickorrist) of Lowee
Noire, Uni, Neptune and Nepgear visit Lowee to play in an amusement park. In this amusement park Rom and Ram are kidnapped by Trick and Linda. After tracking them down using Terra View, a joint Lowee/Leanbox satellite surveillance program, the Goddesses assault the kidnapper's hideout, a construction site in the amusement park. Black Heart defeats Linda as she flees.
A Weekend (Girls' Night) in Leanbox
Noire is seen with the other Goddesses attending a concert in Leanbox by 5pb. After the concert the Goddesses find Vert in her messy room busy and unable to attend to concert or after party. Noire decides to take charge and prepare for the party. She catches Neptune slacking off and gets her back on task.
During the party Vert shows off her new gaming device with Noire and Neptune as the testers. The two are transformed into Dogoos and fight each other. Neptune gets the upper hand the Goddesses have fun.
A large outbreak of monsters occurred in a waste disposal plant in the Zune district. The Goddesses transform into their HDD form and attack the monsters. The Hearts have a small competition to see who can exterminate the monsters the quickest. Black Heart wins this competition.
Suddenly wires bind the Hearts. Arfoire appears with Warechu and throws the red crystal which forms a prison field effective capturing the Hearts. The red crystal are revealed to be anti-crystal, a stone to cuts off the Heart's connection to their shares. Warechu proceeds to take embarrassing pictures of the Hearts to crash their shares. Noire and the other Goddesses can only struggle.
The Resolve (Turn) of the Younger Sisters
They slowly drain the Hearts of their share energy reverting them to their human form. Noire then remembers her lost transformation in Toruune Caves. Noire remains imprisoned in the anti-crystal prison field for the episode.
The Resonance (Limit Break) of the Goddesses
The Anti-crystal eventually turn share energy into anti-energy which can kill CPUs. The Goddesses are buried in anti-energy but refuse to give in to it. Eventually, the candidates defeat Arfoire break the anti-crystal prison field freeing the Goddesses. Noire hugs Uni, proud of how her sister has grown.
The plan to crash the shares of Goddess has failed. Noire and Uni regain their lost shares by exterminating monsters in Lastation.
The Secret (Your-Eyes-Only) of Lastation
Noire enters an office and furtively locks her door. She starts undressing and is excited to try out some new outfits, however someone is peaking.
The next day, the Goddesses gather in Lastation discuss online security with Noire bragging that Lastation's security will never be breached. Unfortunately, Blanc said that it was breached and Vert introduces a programmer Zilge who promptly tracks the hacker's hideout. Meanwhile Nepgear puts cameras all around Noire's office to help Uni figure what Noire is doing in that office at night. Nepgear finds other cameras and traces them back to the hacker. The Goddesses raid the hideout.
In the hideout, they meet the hacker, "Anny" (Anonydeath). Anonydeath reveals his collection of Noire photos. Vert recognizes the cosplay from Four Goddesses Online, Blanc comments on how she would die of embarrassment if that happened to her and Neptune says that Noire looks really cute. Flustered and angry, Noire transforms into Black Heart to attack Anonydeath who defends himself with the monitor containing Noire's photos.
Anonydeath escapes to be stopped by the CPU candidates. Black Heart and Goddesses catch up and arrest Anonydeath.
Later Uni and Noire discuss cosplay and suddenly a girl falls from the sky landing on Noire. She introduces herself to be Plutia, the CPU of Planeptune.
The Paradise (Island) Forbidden
Noire and the other CPUs, Plutia and Nepgear arrive in R-18 island, a resort to investigate some sort of weapon detected by Terra View. They are lead by Linda, supposedly reformed trying to make an honest living by being a guide to a beach.
They are lead to a nude beach where "mysterious light grass" covers the private part. Neptune disrobes her swimsuit to have fun while Noire refuses to disrobe. Neptune teases Noire by throwing the "mysterious light grass" at her saying she looks nude and may as well actually strip. Noire was paralyzed with embarrassment while Blanc reveals that the grass creates a mirage that makes them look naked.
The group indulge themselves in the beach. Noire and Neptune play beach volleyball. Eventually Linda reveals her true colors drugging a iced drink which Neptune drinks. The drink causes extreme shyness for the drinker. When Linda is found out Plutia reforms her and the Goddesses continue on their search for the artillery battery. It appears to be loading to fire and the Goddesses get ready to stop it and it then fires bubbles and beach party begins. Noire thinks she sees Anonydeath on top of the battery but no one else seems to notice.
The Challenge (Rebellion) of Eden
Noire, as her HDD and the Hearts investigate the new nation formed by R-18 island. The artillery battery does time does get ready to fire but fires balloons. Anonydeath appears to welcome them to their nation. Black Heart wonders how he could have gotten out of jail but Anonydeath said they only captured his double. Black Heart states she will take him down but Anonydeath states she has not jurisdiction to do that because they are a nation, Eden.
Black Heart proceeds to attack when a yellow haired girl in a white suit lands on Noire. The girl introduces herself as Yellow Heart. Noire tells her to get out of the way and Yellow Heart begins to get serious to fight the Hearts. Yellow Heart does well to hold her ground but is eventually beaten back to reveal that she is Peashy.
Rei Ryghts then demands the right to export their adult products or else war is declared and soldiers surround the Hearts. Black Hearts states they do not have shares but Anonydeath says that will change.
The Battlefront (Conflict) of Oblivion
Riots are happening all over the four landmasses as people emitting black auras want freedom of expression and more adult content. Uni discusses this with Noire and how the riots are happening in Planeptune and how Nepgear will be the one to handle it. Uni wants to help but Noire tells her to worry about their nation first.
Noire transforms to Black Heart and tries to call Neptune. When she gets through she tells Neptune to stop worrying and defeat Peashy already. Neptune, however cannot get herself to do it and the call ends. Black Heart wonders if she was too harsh against Neptune. She arrives in R-18 island.
There, Plutia is also found and Plutia wonders what she is doing in the island. Black Heart replies Uni is taking care of them. Plutia spots Linda, transforms to Iris Heart and captures her while Black Heart finds the artillery battery. Anonydeath transforms the artillery battery to a sound emitting satellite to down Black Heart.
Iris Heart was able to get in the battery control room thanks to Linda, ties up Rei Ryghts and wants to punish Anonydeath. Anonydeath states he would prefer that from Black Heart who cuts her way into the control room. Iris Heart then lashes her whip revealing a machine that the two CPUs assume to the source of Peashy's power. They destroy it.
The riots around the four landmasses stopped. Eden's invasion of Planeptune and Eden itself is done for. Peashy's transformation ends allowing Neptune to capture her as they plummet into a river.
It was time for Peashy and Plutia to return to the their dimension and Noire is part of the group that sees them off.
The Emissary (Aggressor) of Old
Planeptune's shares have skyrocketed after the defeat of Eden. However, every other nation's share is at an all time low. Neptune decides to host a party at her Basilicom turning it into a fun fair. She tries to invite the Goddessess but they rejected at Neptune's precieved insensitivity. However, Neptune manages to get Noire to take the invitations allowing her to change her mind if needed.
While Neptune is hosting her party, Anonydeath calls Noire over for a talk. Noire, clearly unamused wants the reason for his talk. Anonydeath said he traced his anonymous employer and reveals her to Rei Ryghts. She was the mastermind for the Eden plot. In Planeptune Rei Ryghts reawakens her nation Tari and causes havoc in Planeptune cutting off all communication.
The Ties (Bifrosts) of Tomorrow
After Purple Heart is trashed by Rei, Black Heart, along with Black Sister, Green Heart and 5pb. to provide support. They figure out that Rei's power is coming from the device that gave Peashy power. They try to find and destroy it but Rei's defenses prove too strong.
Rei attempts to destroy Planeptune with a Pong Laser when White Heart and White sisters arrive to reflect the laser with ice. White Heart then throws her axe destroying the share stealing device. Purple Sister joins the fray to defeat Rei Ryghts as she attempts to use her remaining power to destroy Planeptune and Gamindustri.
Eventually the Goddesses are able to pull through to stop Rei's Pong Laser so she tries to take Gamindustri down with her. The CPUs and their candidates surround Rei blocking the damage but are knocked out in the process. Rei still tries to use the last of her energy to destroy the CPUs and the world while they are knocked out. Arfoire and Warechu arrive to use their anti-crystal to destroy Rei's share crystal.
Months later, the Hearts arrive for a ceremony just like the first episode. Purple Heart reverts to Neptune and tears the friendship treaty saying they are true friends now. The Hearts and their candidates then have an exhibition fight for the crowds.
The Eternity (True Ending) Promised
Noire shows her concern with the other Goddesses since their sisters are all having bad nightmares as a result of the Bad End Syndrome. While discussing a cure, Histoire tells them they need tea made from a Shimmering Flower. Noire and Blanc choose to go to a cave in search for the flower while Neptune and Vert head for the Ultra Dimension.
There Neptune lands on the Ultra Dimension Noire since she cannot transform. Neptune comments on how her Noire has no friends. The Ultra Dimension Noire along with the other Ultra Dimension counterparts help Neptune and Vert look for the flower in the Cursed Hell Devil Death Bloody Spectral Tower. However, they have a 3 hour limit before they are stuck in Ultra Dimension for 3 years.
Shimmering Flowers are found on the top floor out of 10,000 floors.The group takes an elevator to the 10000th floor. There the Goddesses choose to fight the monsters while Neptune, Vert and Peashy look for the flower. Neptune chooses to stay back and help Peashy fight monsters while Vert returns with the flower to the Hyper Dimension. Due to a malfunctioning Warp Gate, Neptune opens a portal to the Hyper Dimension in the cave where her Noire and Blanc is at.
Ultra Dimension Noire asks Hyper Dimension Noire if she has no friends. Hyper Dimension Noire replies with a shocked "What?". The Ultra Dimension Goddesses and the Hyper Dimension Goddesses are seen at the end visiting each other. The two Noires have fun with cosplaying with Uni watching in the background.