Kagerō

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

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

Abilities
Though she was actually a young girl, Kagerō constantly disguised herself as a grotesque, hunchbacked man with buck teeth. This transformation was not dispelled when she was wounded. 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.

Kagerō can use a fire technique that releases a flammable gas and can access a Fūma 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.

Land of Rice Fields arc
Kagerō, along with Kamikiri and Jigumo, attacked Naruto Uzumaki and Sakura Haruno when they were hiding in a temple with Sasame. She then used the Antlion technique to suck Naruto into the ground. Gama, Jiraiya's toad, used his tongue to pull Naruto out of Kagerō's pit, which Naruto took advantage of by wounding Kagerō with his Rasengan, causing her to retreat.

Though she was wounded by the Rasengan, Kagerō showed up at the second battle after Sasame drugged the Leaf ninja's drinks. She told Sasame that if she helped them capture the Leaf ninja, they would take her to see Arashi. However, Sasame realized that Kagerō 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 Fūma and bring them out into the open. During the second battle, Kagerō 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 Kagerō, he refused due to their failure to kill the Leaf ninja. After Orochimaru killed them, he did heal Kagerō. Kagerō encountered Sakura in Orochimaru's hideout while posing as Kabuto Yakushi. Kagerō 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.

Trivia

 * Kagerō can be translated or.
 * The mayfly is a reference to her remarks of how life is ephemeral, similar to a mayfly.
 * The heat haze is a reference to Kagerō's ultimate technique, which has fire-like properties, as well as having a fire-nature technique.