Croire is a tome similar in nature to Histoire. However, whereas Histoire can establish connections with her counter-parts across dimensions, Croire has the ability to directly traverse dimensions. She plays the role of an observer stirring up trouble for her own entertainment, rather than a direct antagonist.
Croire is a pale-tan skinned girl with bright blue eyes and choppy, platinum blonde-white colored hair worn with black ear pieces with red on them. She has a pair of purple and blue gradient themed wings and wears a black dress with silver and red accents, a crimson ribbon tied around her right wrist, and a cape like piece that attaches to her top by the big pink orb in the center of it. With smaller pink orbs below her shoulders.
Croire has a very crass way of speaking and has tomboyish mannerisms to fit her tomboyish look. She uses derogatory terms to describe people rather frequently and definitely hates when people can't get her name right. Croire is shown to have little to no concern about anyone who gets mixed up in her trouble causing because all she cares about is her own entertainment.
Croire first appears in the Hyper Dimension after Rei runs out of fear from Neptune and Nepgear and ends up finding herself lost in the city, claiming to have been searching for her for ten days. Fulfilling a request from the Rei of the Ultra Dimension, she force feeds a parcel of dark power into her, which later allowed Rei send Neptune to the Ultra Dimension. She then lets the other Rei know about this development, who meekly informs the other Seven Sages of the development.
Croire appears again in Chapter 5 when Rei had abducted Peashy as a hostage, and starts bullying her. While they were arguing, Peashy began rummaging in Rei's personal affects and tried to eat a CPU Memory core, awakening her as a goddess. Croire is seen again only after the Seven Sages disbanded following Yellow Heart's defeat, who gets incredibly annoyed that she wants to go to the PlaneptuneBasilicom and turn herself in. With the help of the other Rei, Croire forces Ultra Dimension Rei to regain her CPU powers, whose personality rap[idly unhinges and plots against the goddesses directly.
After the party captures Rei following her defeat, she is taken to the Basilicom for questioning about how she was able to transform. Croire eventually arrives as Rei was about to explain how power was transferred between dimensions. She reveals to have knowledge about Histoire's purpose of creation which is to record the history of the CPUs and weave realities, but doesn't actually disclose her own purpose behind existing other than to "liven up history." She also reveals that unlike Histoire she can't make a connection to other worlds, but she can travel to them. Before she leaves, Croire warns Rei and the others that the Hyperdimension Rei is going to destroy their world right before as the interdimensional assault begins.
During the "Rei's Memories" events, it is shown that Croire has always been with Rei ever since she became a goddess by accidentally eating a CPU Memory, much like when Plutia did the same exact thing and Histoire appeared. Croire explains that since Rei is a CPU that she must form her own nation. When the people begin to revolt against Rei's tyrannical, she ends up destroying her nation (having not realized her power comes from faith). Croire is surprised to see that she is still alive after all that destruction she caused by releasing all of her power at once, and admits to being uncertain as to whether her becoming a goddess was a cosmic mistake.
During the True End Route, Croire observes the fight between the Hyper Dimension Rei and the other goddesses from her "front-row seat." When the Ultra Dimension Rei arrives in an attempt to persuade the other Rei, Croire instead taking the remaining power that she brought over and transfers it to the Hyperdimension Rei so that she can continue fighting. When Purple Heart asks her what her motive is, Croire states that all she wants is to be entertained. After the goddesses successfully take down Rei and get rid of the dark power, Croire leaves the Hyper Dimension in search of somewhere else to stir up trouble.
When she finally arrives at her destination, she is suddenly captured by the Neptune from the Ultradimension with a butterfly net, who mistook her for a rare bug.
Hyperdimension Neptunia Re;Birth3: V Generation
Croire's role remains the same from Hyperdimension Neptunia Victory.
Megadimension Neptunia VII
Zero Dimension Neptunia Z: Twilight of the Desperate CPU
Croire finds a share crystal. She decides to keep it around while looking for something interesting to record in history. She finds Arfoire. After some chatting, Croire finds Arfoire interesting and allies herself with her. Croire is excited about the possibility of recording the end of a world with her. She also mentions that has Rei Ryght's power. The two decide to use the share crystal to lure the group.
The group arrives and Neptune complains to Croire about leaving her. She apologizes and asks Neptune to join her because it is way more interesting than the other group. Neptune declines so Croire says she has been infected with their boredom. She clarifies to the group that she is not their ally and is allied with whatever is interesting. She is impressed that Nepgear remembers her despite Nepgear's horrible treatment in Hyperdimension Neptunia Victory.
Arfoire then finds herself defeated and asks Croire for the Rei Ryghts' power. Croire gives it to her as that will make things interesting. Arfoire gains the power and revives Dark Purple. She then wounds Uzume forcing the group to retreat. She tries to blow them all up with Dark Purple. Croire protests as that will injure her as well. Arfoire does not care. Croire follows Neptune and flees.
As punishment for Croire's earlier actions, Neptune imprisons Croire in her specimen book, the Nep Note with tape so she cannot escape. Croire protests this as she did not know Arfoire was suicidal. Croire has a chance to get out however, if she helps Nepgear and Neptune find "Oratorio's Tangram" and "Jingu Cherry Blossoms", Neptune says she might be let free. Croire says they drop from monsters and wants the girls to gather them as quickly as possible. When they gather everything Neptune retracts her offer. Croire claims she tricked her but Neptune says she only took advantage of her.
Croire and Neptune then go scouting. They notice Arfoire has merged with Dark Purple. The two rush back to the group and update them about that. They have about a day until Arfoire arrives.
The next day, Nepgear lays out the plan. The fused Arfoire is accompanied by a horde of monsters. Nepgear and Neptune are to divert the monster into some ruins when Arfoire passes them. That way Uzume can use her sharing field. Croire wants to be in the sidelines of all this. Neptune brings Croire along in the frontlines as she wants her to record the history of the girls saving the Zero Dimension. Croire demands that her safety be their number one priorty.
They try to enact this plan but Arfoire can nullify the share energy. Croire says that should not be possible. Arfoire begs to differ. Umio then arrives with the monsters and a whole bunch of share crystals. However, even that is not enough. Histoire and the small Neptune then offers Planeptune's shares. The two Neptunes encourage Nepgear and Uzume. Nepgear is able to resonate Planeptune shares with Uzume and they create the sharing field. The small Neptune then arrives to take part in the final fight against Arfoire.
The girls then engage in their final fight against Arfoire. They come out victorious and Arfoire's Dark Purple body collapses. The smaller Neptune the notices Croire in her weakened state. She wonders if Croire has learned her listen. Croire says she did nothing wrong, and only recorded the history of the world. Smaller Neptune wonders if she should punish Croire. Croire refuses to be punished by her and flies off. The older Neptune runs off after her. With that Croire was able to record the climatic battle that decided that the Zero Dimension would be saved.