Warning: There WILL be unmarked spoilers. If you do not wish to be spoiled, please do not read this.
Zaraki Kenpachi is the captain of the Gotei 13’s 11th Division. He is one of the many Bleach characters with a very unique appearance. His hair is spiked with tiny bells at the tip of each spike. His huge size and height (he is taller than Sado Yasutora) together with the deep scar on his face makes him look extremely aggressive and wild. And unlike Sado who is gentle and contrary to his appearance, Zaraki is indeed a violent man who has deep passion for fighting. Zaraki lives for combat. Injury, pain and death are nothing but necessities in order for him to enjoy a good fight.
Although aggressive, Zaraki’s compassion can be seen from his concern for his young lieutenant, Kusajishi Yachiru. Ever since Zaraki found her, they’ve built a strong father-daughter kind of relationship. And Zaraki’s other lieutenant has shown great respect for him, which hints that Zaraki is in no way a monster that knows only bloodsheds.
Before Zaraki became captain, he was a wandering swordsman from Rukongai who is very proficient in sword-fighting. When he found his way to the Court of Pure Souls, he defeated and killed the previous 11th Division captain and took over his position.
Zaraki Kenpachi’s Zanpakuto
Zaraki is the only captain of the Gotei 13 that is unable to perform both his zanpakuto’s Shikai (Initial release) and Bankai (Final release). The reason is due to Zaraki not knowing his zanpakuto’s real name. He has always depended on his own strength, power and sword-fighting skills to defeat his enemies, therefore he has never understood the need to know his zanpakuto’s name.
However, since his fight with Kurosaki Ichigo, Zaraki has begun to realize the pain of not having a name. Being able to relate to his zanpakuto’s pain, he has decided to learn his zanpakuto’s name. This is partly due to his interest in growing even stronger to defeat Ichigo in another fight.