He is voiced by Hidenobu Kiuchi in the Japanese version, who also voiced Squalo, Sale and Melone in JoJo's Bizarre Adventure: Golden Wind, Hol Horse in JoJo's Bizarre Adventure: Eyes of Heaven, Saguil A in Doubutsu Sentai Zyuohger, Chaos Sorcerer in Yu-Gi-Oh! GX, Wingul in Tales of Xillia, Ethan Winters in Resident Evil 7: Biohazard, Hei in Darker than Black and Kenzo Kenma in Monster, and by Todd Haberkorn in the English version, who also voiced E.N.D. and Natsu Dragneel in Fairy Tail, Petelgeuse Romanée-Conti in Re:Zero − Starting Life in Another World, Nobuyuki Sugou in Sword Art Online, Ayato Kirishima in Tokyo Ghoul, Shockwave in War for Cybertron, Puppetmon in Digimon Emperor, Judar in Magi: The Labyrinth of Magic, Digimon Emperor in Digimon Adventure 02, Android 19 in Dragon Ball Z, Assassin in Fate/Stay Night, Apos in Rin: The Daughters of Mnemosyne, Baatar Jr. in The Legend of Korra, Jadiete in Sailor Moon Crystal, Bellion in The Seven Deadly Sins, Aleistor Chamber in Black Butler, Ryōsuke Todoroki and Shirō Iori in Kill la Kill, Kyrie Illunis in Sands of Destruction, Firo Prochainezo in Baccano!, Masao Murasako in Shiki, Korekiya Shinguji in Danganronpa V3: Killing Harmony, Shikadai Nara in Boruto: Naruto Next Generations, Aru Akise in Mirai Nikki, Teruteru Hanamara in Danganronpa 2: Goodbye Despair, Allen Walker in D.Grey Man, Tsukune Aono in Rosario x Vampire, Death the Kid in Soul Eater, Ling Yao in Fullmetal Alchemist, Kinji Tohyama in Aria the Scarlet Ammo, Slapback and Grey Matter in Ben 10, Keroro in Sgt Frog, Kimihiro Watanuki in xxxHolic, Italy in Hetalia, Khamsin Nbh'w in Shakugan no Shana, Raki in Claymore, Rowen J. Ilbert in Tales of Xillia, Sparrow Hood in Ever After High and Yamato Akitsuki in Suzuka.
As Nero was a new candidate, he only could use four of the six Rokushiki techniques: Soru, Geppo, Kami-e, and Rankyaku. His lack of Tekkai and Shigan made him unable to block powerful strikes and pierce opponents, respectively. To compensate, he evaded enemy strikes carefully with Soru, Geppo, and Kami-e; for offensive, along with slashing with Rankyaku, he used a pair of pistols instead of stabbing with his fingers. He was at least skillful enough to have one variation of Rankyaku.
Nero may not be very strong compared to the other, fully-trained CP9 agents, but he was still quite intelligent, since he figured out that the attackers on the Puffing Tom would try going along the roofs of the train cars in order to reach the one containing Nico Robin as easily as possible, and he was able to quickly deduce that Franky was vulnerable to attacks aimed at his back. Alas, this was not enough to impress his assessor, Rob Lucci.
Regardless to his creative improvising and analytical nature, his lack of mastery of Rokushiki caused Rob Lucci to claim Nero was "worthless" to the unit, leading to Nero's rather brutal dismissal.
Nero attempted to stop Franky from rescuing Robin but failed and was punched through the roof of Puffing Tom, into the cart where the rest of CP9 was. Battered as he was, Nero continued to try to fight Franky and stated he would kill him, but Lucci would not allow this, as they were simply supposed to capture him. Displeased that Nero failed in his task, Lucci gave Nero three seconds to escape, who was too slow to grasp the notion that he just got fired. At which point Lucci quickly took him out with five Shigan attacks. Lucci then personally expelled him from CP9 and Nero's wounded body was thrown into the ocean during Aqua Laguna, one of the biggest storms in the world. It is unknown whether or not Nero is dead or alive.