Chrome Dokuro is a central character who serves as the Mist Guardian for the Vongola Family's tenth generation. Her real name is Nagi, a lonely and neglected girl who suffered a severe traffic accident while trying to save a cat. The accident destroyed most of her internal organs and her right eye. While she was hospitalized and ready to die after overhearing her parents express no desire for her to live, she was saved by Mukuro Rokudo. Mukuro used his powerful illusion abilities to create illusory organs that sustain her life and gave her the new name Chrome Dokuro, inviting her to join him.

In terms of appearance, Chrome is a short, slim, and petite thirteen-year-old girl with short purple hair styled into a distinctive shape resembling a pineapple, a hairstyle forced upon her by her ally Ken Joshima which she ultimately came to accept. She wears an eyepatch over her damaged right eye, typically adorned with a skull pattern. Her primary weapon is a trident, which serves as the focal point for the illusions maintaining her artificial organs; if the trident is destroyed, her illusory organs fail and her life is placed in immediate danger.

Chrome's personality is defined by her traumatic past and the profound gratitude she feels toward Mukuro. She is kind and gentle but extremely shy and timid, particularly when confronted with unconditional kindness from others. This behavior stems from her childhood, where she was neglected by her parents and unable to form friendships. When characters like Kyoko Sasagawa, Haru Miura, and I-Pin attempt to befriend her, Chrome initially runs away from their kindness because she never believed anyone could accept her unconditionally. Bianchi compares her reaction to experiencing a culture shock. Despite her timidity in social situations, Chrome possesses a strong will in battle and does not shy away from danger. However, she initially lacks self-confidence and tends to belittle her own abilities when she fails, relying heavily on Mukuro for support.

Her motivations are deeply tied to Mukuro, the person who gave her a second chance at life. She is fiercely loyal to him, addressing him with great respect and willing to risk her life for his sake. She even studies Italian diligently in hopes of one day conversing with him in his native language. While she loves Mukuro deeply, as the story progresses her motivations expand to include protecting all of her friends, leading her to seek independence and strength on her own terms. As the Mist Guardian, she serves Sawada Tsunayoshi as her boss, and she appreciates that Tsuna is the second person after Mukuro to accept her genuinely. She shows her gratitude and unique personality by greeting Tsuna with a kiss on the cheek upon their first meeting.

Chrome's role in the story begins during the Varia arc, where she appears as Tsuna's Mist Guardian for the ring battles. She fights against the Arcobaleno Mammon and, though initially overwhelmed, allows Mukuro to take over her body to secure victory. Throughout the series, she serves as a vessel and connection to Mukuro, who is imprisoned by the Vindice, allowing him to influence events in the real world. In the Future arc, she is transported to an alternate future where she faces the Millefiore family. After Mukuro is severely wounded by Byakuran, her illusionary organs begin to fail, but she learns to use her own Vongola Mist Ring to sustain herself. She later receives the Mist Vongola Box Weapon, which contains an owl possessed by Mukuro and can transform into Daemon Spade's Devil Lens, an item that allows her to see through any illusion.

Key relationships define Chrome's development throughout the story. Her bond with Mukuro Rokudo is the most significant, as he is her savior and the first person who claimed to need her and accept her. Though characters like M.M warn her that Mukuro may only be using her as a tool to escape prison, Chrome remains loyal and loving toward him, and Mukuro in turn shows exceptional kindness to her, though his true feelings remain ambiguous. He ultimately pushes her toward independence, even kicking her out of the Kokuyo gang so she can stand on her own. With Ken Joshima and Chikusa Kakimoto, Chrome shares a relationship of mutual loyalty to Mukuro. Though Ken is often mean to her, he shows his care through small gestures like buying her favorite sweets, and over time she comes to regard them as her first true comrades.

Her friendships with Kyoko Sasagawa, Haru Miura, and I-Pin represent her gradual integration into a normal, caring social environment. These three girls persistently offer Chrome kindness, and through their gentle encouragement, she slowly learns to accept friendship and open her heart to others. This development is crucial to her growth as a person, helping her move beyond her traumatic past. Her relationship with Tsuna Sawada is also important; she regards him as her boss and fights loyally for him, while Tsuna consistently treats her with kindness and concern, even showing anger toward Mukuro when he believes Mukuro has abandoned her.

Chrome undergoes significant character development over the course of the series. Initially a shy, insecure girl who depends entirely on Mukuro for her very existence, she gradually becomes more open and self-reliant. By the Representative Battle of the Rainbow arc, she faces an internal crisis where she begins rejecting Mukuro's illusionary organs because she wants to be seen as an individual rather than just an extension of him. She resolves to become independent and strong enough to protect everyone she holds dear with her own power, ultimately joining Reborn's team and fighting alongside Mukuro as an equal partner rather than a dependent vessel. Her resolve becomes so strong that she generates her own organs independently, a feat that impresses even powerful illusionists.

In terms of abilities, Chrome is a highly talented illusionist. Both Mukuro and the Arcobaleno Mammon acknowledge her potential. Her primary techniques include creating Real Illusions that can become physically real if the target believes in them, as well as using two of Mukuro's Six Paths of Reincarnation: creating illusions and summoning animals. She can summon venomous snakes through the Beast Path. After Mukuro is freed from prison, she loses access to his techniques but creates her own trident with a single spike instead of two prongs. Through her Vongola Box, she gains the Devil Lens, which allows her to see through enemy illusions. Her illusions are so potent that Mammon admits if they had believed Chrome's illusion for even a second, they would have been defeated. Only a true expert can see through her work, and she eventually becomes strong enough to create her own illusionary organs, a skill that demonstrates her remarkable growth as an illusionist and as an independent individual.