Kagerō

was a member of the Fūma clan. She was among the Fuma clan members who were deceived by Orochimaru. She was one of a three-member group (alongside Jigumo Fuma and Kamikiri Fuma) who guarded Orochimaru's base in the Land of Rice Fields.

Personality
She shows extensive loyalty and dedication to her fellow clan members, using her Ephemeral Vengeance even though it would endanger her life. This same respect is also shown towards Orochimaru, who Kagero views as the person who will bring the Fuma clan back into its glory. She knows of Sasame's bond with Arashi, and Sasame shows her considerable respect, addressing her as "Kagero-sama", literally translated as Mistress Kagero. She constantly made references to the life of a mayfly while in her male disguise, which makes sense, as "Kagero" can mean "Mayfly".

Fuma clan Affair
Kagero, along with Kamikiri and Jigumo, attacked Naruto Uzumaki and Sakura Haruno when they were hidding in a temple with Sasame. He/She then used the Antlion technique to suck Naruto into the ground. Gama, Jiraiya's toad, used his tongue to pull Naruto out of Kagero's pit, which Naruto took advantage of by wounding Kagero with his Rasengan, causing him/her to retreat.

Though he/she was wounded by the Rasengan, Kagero showed up at the second battle after Sasame drugged the Leaf ninja's drinks. Team Kamikiri told Sasame that if she helped them capture the Leaf ninja, they would take her to see Arashi. However, Sasame realized that Kagero and the others were actually planning to kill Naruto and the other Leaf ninja. The Leaf ninja had discovered the drugs and used substitutions to deceive the evil Fuma and bring them out into the open. During the second battle, Kagero molted her male form to use her Ephemeral Vengeance. Jiraiya managed to counter the technique and she escaped with Kamikiri and Jigumo in her arms.

When Jigumo and Kamikiri begged Orochimaru to heal Kagero, he refused due to their failure to kill the Leaf ninja. After Orochimaru killed them, he did heal Kagero. Kagero encountered Sakura in Orochimaru's hideout while posing as Kabuto Yakushi. Kagero tried to kill Sakura, but once again, Naruto wounded her with the Rasengan. She attempted to kill Naruto by synchronizing their heartbeats and stopping hers, but Sasame cut the chakra threads connecting them, and died after warning Sasame about how much Arashi changed.

Abilities
Though she was actually a young girl, Kagero constantly disguised herself as a member of the opposite gender (mostly a grotesque, hunchbacked man with buck teeth). While disguised as a man, she would use the Earth Release: Antlion Technique to cause everything in a certain area to be drawn into a large pit. After removing this form, she is able to use Antlion Ninja Arts: Ephemeral, creating four wings out of chakra on her back. She can then fire a gigantic blast of chakra at her opponent: the amount is said to be so great that this jutsu can only be used once in a lifetime. She can also fly and teleport while in this form. Kagero can also use a fire technique that releases a flammable gas and can access a Fuma clan jutsu that connects the user's and the target's hearts with chakra strings and makes them beat at the same rate - when one speeds up, slows down or stops, the other will, meaning that if the user dies, so will the victim. She also possessed, or was subject to, a transformation jutsu that is not dispelled when the user is wounded. Also, since Orochimaru healed her after killing off Kamikiri and Jigumo, it's reasonable to believe that Kagero was the most powerful member of her team.