Non-existent in Kurumada's original manga, Heavenly Violent Star, Bennu Kagaho (天暴星ベヌウの輝火Tenbōsei Benuu no Kagaho?) is one of the newly introduced Specters of Hades. Kagaho shows loneliness, sadism and rage in battle and determination. He has a rivalry with Libra Dohko., and memories of his dead younger brother Sui, who committed suicide because he felt he was a burden for Kagaho, who always ended up injured when protecting him.
Kagaho is one of the most powerful Specters and also known as the fastest one, being able to fight against Gold Saints at the same level. His ability allows him to create black flames with his Cosmo. His ability with black flames are further revealed with Corona Blast (コロナブラストKorona Burasuto?)in which Kagaho creates an enormous sphere of fire similar to a star, then shoots it at his opponent. Kagaho is also seen using this technique consecutively. His Crucify Ankh (クラシファイアンクKurashifai Anku?) allows Kagaho to shoot many black fire stakes that enter into the body of the opponent and start burning him from the inside. Then the black fire binds the opponent until the body is destroyed.
In his fight against Taurus Aldebaran, Kagaho is overpowered but the Gold Saint spares him saying that he didn't sense true evil in him. The fight also left him with his damaged Surplice, as only one wing remained. After the fight Kagaho seems to become more calm and even started to respect Aldebaran. He was also seen after the demise of Taurus briefly encountering Pegasus Tenma. Afterwards he received an upgrade in his surplice, and was sent to punish Garuda Aiacos for failing to keep the Saints at bay; it was hinted that Kagaho took on the role of Aiacos as a commander. He later reappears invading Sanctuary, preparing to extract Athena's blood from Dohko's veins, to revive the goddess' Cloth, as requested to him by Hades. Kagaho reveals that the eventual acquisition of Athena's blood was the reason for sparing Dohko's life. Triggering Athena's Cloth resurrection with Dohko's blood, the Specter snatches his reward, leaving Libra for dead. Kagaho is then stripped of Athena's Cloth by a moribund Dohko, much to his surprise. Bennu is prevented from pursuing him by Gemini Defteros using the technique Another Dimension to save Dohko's life.
Kagaho reappeared right after Alone slaughtered his Skeletons, standing in Pandora's path as she tried to go on a pursuit after Hades' vessel. Bennu revealed that he was aware that their god was Alone all the time, and that his loyalty towards him remained despite this. Challenged by Pandora, he surprisingly allowed her to pass, stating he understood her desire of wanting to be reunited with her younger brother.
The Bennu Specter last appeared preparing to prevent Athena and her Saints trespassing the Third Demon Temple: Terra (第3 魔宮地球Dai san Makyū Tera?), which was presented by an Ankh of black fire, in his words, the grave of his human feelings. Kagaho ensnared Regulus and Tenma with his Crucify Ankh, as well as Athena as she rushed to their aid. In the moment Kagaho was to take their lives, he was stopped by Libra Dohko. The Specter then prepared to engage Libra in battle to the end. After witnessing Dohko's upgrade in power because of having Athena's blood running through his veins, Bennu seeks to evaporate that blood from Libra's body, exhibiting a new technique, Rising Darkness(ライジングダークネスRaijingu Dākunesu?), which creates a small, black sun which raises the temperature similar to that of desert environments, dehydrating the victim. Bennu is then confronted by Dohko, who reveals he has seen the Specter's true nature, and intends to bring it back. Kagaho explodes in anger, brutally attacking Dohko. The Libra Saint learns about Kagaho's brother after colliding with the Ankh, and then stops Bennu's attack. Kagaho is held by Dohko as the latter prepares to use his final technique, which would send them both flying to die in outer space. As they both leave the stratosphere, Kagaho admires the Sun while listening to Dohko's reasoning, and brings back memories from his past when he lived with Sui. The Specter's Cosmo and flames then change color, and an aura similar to the Phoenix Bronze Cloth's wings appear behind him, while Kagaho realizes the truth and has a change of heart. Kagaho reminisces about his motivations and loyalty towards Alone. At last, Kagaho burn into the skies becoming a phoenix, vowing that, if given the chance, he will protect Alone and the Earth in another life.