Fullbring is a special ability which certain Humans are born with, in which they can manipulate the "soul" of matter for a variety of effects. Fullbringers each have a parent who was attacked by a Hollow before they were born. Traces of the Hollows' powers remained in their mothers' bodies, which were then passed onto them when they were born. Thus, the powers resemble those of Hollows more than they resemble those of Shinigami's.^[1]
Unlike other powers, the Fullbring abilities do not and cannot change through growth. However, Fullbringers must progress to a certain level before they can use their abilities to their fullest.^[2] As such, the Fullbring of a user that has not reached such a level appears to be different, and can be considered "incomplete".^[3] When the Fullbring reaches its full potential and evolves to their final stage, it will emit a violent burst of energy that can damage the user's body. Therefore, another Fullbring user is required to oversee the process in order to block the explosion and prevent the recently complete Fullbring from damaging its user.

Ichigo looks like a normal teenage boy; the one exception to that is his spiky orange hair, a trait that he has been ridiculed about for years. He is a fairly tall, lean-built person with peach skin and brown eyes. He has a tendency to wear shirts patterned with the number 15, because his name is a homonym for the number . Since becoming a Shinigami, he has become noticeably more muscular, as noted by his sister Karin. When in his spiritual form, Ichigo wears standard Shinigami attire with the addition of a strap across his chest. Initially, it was a thick brown belt to hold his Zanpakutō sheathe, but it later became a red rosary-like strap. The shape of them is a kite with a flat top and bottom. Ichigo's appearance has caused several people, including Jūshirō Ukitake, to notice a similarity to Kaien Shiba; the former lieutenant of the 13th Division After training in the Dangai, Ichigo's hair grows considerably and is noticeably taller, as stated by his friends. However, after Ichigo loses all his spiritual powers, his appearance reverts to the way it was before his Dangai training

A year and a half later, unlike his friends, Ichigo's appearance does not change beyond growing taller. After regaining his powers, Ichigo’s Shinigami attire also consists of a thicker strap across his chest. He also has four black vertical lines on his forearms and black bands with white ends crossing over his chest, wrists, and ankles. Similar bands are around his neck as collars and covering his forearms. Kugo speculated these changes are influenced from Ichigo's Fullbring.