Ikkaku appears as an average sized man with a bald head, which has often caused irritation particularly when others call him "baldy." He wears a regular black hakama common to all shinigami, however he doesn't wear socks with his scandals. His most distinguishing feature are the small crimson marks above his eyes.
Ikkaku is generally jovial, outgoing, and humerous. However, he does become more reserved and serious when the situation calls for it. Ikkaku has a deep passion for battle, a sentiment shared by his captain and all other members in his division. As a result, his most joyful moments are often when he is embroiled in a fierce battle against his toughest enemies. Driven by strong determination, Ikkaku longs to become the most powerful warrior he can be, primarily surpass his captain Kenpachi Zaraki and his rival Iba Tetsuzaemon. Ikkaku, though in a peculiar way, is mostly friendly and even courteous under some circumstances. Nevertheless, he can become easily irritated, especially when anyone refers to him by his bald head.
Ikkaku once lived in Rukongai, and traveled around looking for fights with strong opponents. One day he came across Kenpachi Zaraki and battled with him. Ikkaku was defeated, and as Kenpachi was about to leave, Ikkaku asked why he hadn't killed him, and Kenpachi replied saying that luck was on his side, and he should now live to kill the person that spared him. Soon after, Ikkaku found out that Kenpachi became captain of the Gotei 13's 11th Squad, and so he decided to become a Shinigami and serve under Kenpachi.
Ikkaku, since before he graduated from the Shinigami Institute and joined the Gotei 13, is exceptionally proficient at swordsmanship. After becoming a shinigami, Ikkaku developed a peculiar, unique style of swordsmanship in which he fights with the sword and its scabbard. However, he can only use this style of combat while his zanpakutō is still in its sealed form. He makes frequent use of shunpo (lit. "flash step"), but refuses to use kidō as it goes against his division's ethic. His power and skills mainly draw from his long years spent in combat, which can be attributed to his eventual achievement of bankai.
Ikkaku's zanpakutō is called Hōzukimaru (lit. "Demon Light" or "Winter Cherry"). Although it appears as a regular zanpakutō in its sealed state, it has blood-clotting ointment stored in its hilt. Upon its release, Hōzukimaru transforms into a yari with a wax wooden shaft. Although he generally treats it as such, Ikkaku often disjoints the shaft into a three section staff in order to surpise his opponents. Ikkaku, uncommon to shinigami of his rank, has achieved bankai, though he prefers to keep it a secret so as to avoid being pressured into becoming a captain.
Hōzukimaru's bankai, called Ryūmon Hōzukimaru (lit. "Dragon Crest Demon Light"), takes the form of three massive weapons connected by a thick chain: two giant blades in each hand and a fan shaped blade, adorned with a Chinese dragon crest, floating behind Ikkaku's back. Ryūmon Hōzukimaru is an unusual bankai because it has no special abilities other than the vast increase in power. As a battle progresses, the dragon crest acts as a meter gradually glowing crimson. When the whole crest is glowing, all of Ryūmon Hōzukimaru's power is unleashed.