Renji Abarai (阿散井 恋次 Abarai Renji ) is the lieutenant of the 6th Division in the Gotei 13 under captain Byakuya Kuchiki. Renji's zanpakutō is Zabimaru (蛇尾丸, roughly "snake tail"). Zabimaru is a nue (a baboon with a snake tail), hence his name. Zabimaru's spirit is portrayed as battle-loving and proud, similar in personality to Renji. Both the snake and baboon are capable of speaking, though the baboon is usually the more dominant one.
Zabimaru's shikai command is "howl" (咆えろ hoero ), although in the English adaptation of the anime the term used is "roar". In such state, it transforms into a segmented blade with a pick-like protrusion on each segment. The segments are connected by a stretchable thread, making Zabimaru more useful as a whip than an actual sword. While Zabimaru can be stretched to incredible lengths in its whip form, Renji has a limit of three consecutive attacks before having to bring the segments of Zabimaru back together for recovery. Renji can also use his spiritual power to separate the segments and surround an opponent with them, allowing him to execute a one-shot omnidirectional attack called higa zekkō (狒牙絶咬, "bite of a baboon's broken fang").
Zabimaru's bankai is Hihiō Zabimaru (狒狒王蛇尾丸, "baboon king snake tail") and transforms Zabimaru into a massive version of its shikai form resembling a skeletal snake. Unlike its shikai, Zabimaru's segments are held together by Renji's spiritual power, allowing him to separate and reattach them at will. Even if a segment is damaged, Renji can simply detach it and reform Zabimaru. Zabimaru itself, in bankai form, does not literally "cut", Renji usually catches his opponent with the snake-head of his weapon and smashes his opponent into the ground with it. Zabimaru also gains a special technique known as hikōtsu taihō (狒骨大砲, "baboon bone cannon") after Renji becomes more adept with using his bankai. The technique fires a dense blast of spiritual energy from Zabimaru's mouth. He can also use a much more powerful higa zekkō, where all the segments detach and sharpen using spiritual energy.