Renji has long red hair, often dubbed "crimson" which he keeps usually in a high ponytail. His upper body is covered in tribal tattoos. It appears that with every achievement that Renji gets, his tattoos increase. This started from his starting days as a Shinigami candidate. At the moment, his back ,chest, stomach are covered with tattoos. He also has them on the top of his thighs and his neck. Also he has them as eyebrows. Interesting.
Renji has brown eyes and long crimson hair, which is usually kept in a high ponytail. His upper body is covered in tribal tattoos. The amount of tattoos has increased over time, starting from his early days as a Shinigami candidate to covering his entire back and much of the front of his body and his extremities.He wears the standard Shinigami outfit, though he usually includes some sort of headgear, usually expensive glasses or a white headband when he is saving up to purchase some new glasses. While out of uniform, Renji often wears a white kimono-like type of night clothing, with pink floral patterns on it, and a dark grey sash tied around his waist, with bandages underneath. It has also been said 'that the women within his Division do not mind that he usually walks around in his night clothing'.
Renji is quite dynamic. He varies from smug and cocky to disquieted and depressed after his major defeats, but shows himself to be an incredibly serious and determined fighter when confronted with an actual challenge. Willing to fight, kill, and die for whatever he believes in, Renji is a dangerous man to those who stand in his way. Yasutora Sado compares him to Ichigo Kurosaki when fighting. Renji likes taiyaki (a popular fish-shaped pancake usually filled with sweet bean paste) and dislikes spicy food. Renji likes futsal, and in his free time works on assembling a team from the 6th Division, with success, more or less. The current members are himself, Rikichi and the 4th, 8th, 13th and 20th seated officers.
Zabimaru (蛇尾丸, Snake Tail): Zabimaru's sealed form resembles a typical katana. It has a rectangular bronze tsuba with a jagged design to it and a red handle and sheath.
Shikai: Zabimaru's Shikai command is "Howl" (咆えろ, hoero; "Roar" in the English dub). In its Shikai, Zabimaru transforms into an even longer 6-part segmented blade; each segment is wider than the one preceding it from the hilt with 2 pick-like protrusions on the front and back of each segment, with the ones on the front much longer than the ones at the back. Zabimaru's segments grow in number almost without limit. The segments are connected by a stretchable thread, making Zabimaru more useful as a whip than an actual sword, though it can serve as a regular sword just as easily, thanks to Renji's swordsmanship. Zabimaru's guard and handle remain the same in its Shikai release. 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 - which makes him fairly vulnerable during the time interval. To make up for this, Renji usually relies on Shunpo for evasion as he retrieves Zabimaru's segments. Renji's Shikai, while durable to an extent, can ultimately sustain serious damage the longer the fight drags on. While it can withstand dangerously prolonged combat, it has limits in enduring high-level attacks that are conducted by either the enemy or by Renji himself. Because of these many drawbacks, Renji states that out of all the other Zanpakutō wielded by the other lieutenants, Zabimaru is the most difficult to master.