Zabimaru (蛇尾?) is a Zanpakutō owned by Renji Abarai who originally appeared as Nue and later splintered into two separate yet linked entities: An adult green-furred woman called Saru and a red-haired small boy with a snake tail called Hebi. Though attached by the chain, they can temporary severe it to act independent of each other. Like their owner, Zabimaru's halves share Renji's desire to get stronger. Under the influence of Muramasa, Zabimaru battled fought Renji and gave him a hard time in battle until Renji uses his Shikai to defeat Zanpakutō as Saru and Hebi aid him in the battled to come until they revert back into their Zanpakutō form once Muramasa's ability wears off.
In the japanese version, the original form of Zabimaru is voiced by Toru Furusawa, Saru by Mitsuki Saiga, and Hebi by Asami Sanada. In the English, while Vic Mignogna voiced Zabimaru's original form, Saru is Mary Elizabeth McGlynn while Hebi is voiced by Michelle Ruff.
Read more about this topic: Bountos, Non-Soul Reapers, Zanpakutō Spirits