The world of Bleach is one of souls and those who govern those souls, the Shinigami. This theme starts right at the beginning, with Unification occuring during Ichigo's first encounter with Rukia and his first Hollow battle.
In a world that is seemingly normal, Ichigo Kurosaki stands out. Not just because of his hair or lax manner, but because of his ability to see spirits of those who have left the world. A chance encounter with Rukia Kuchiki, a Shinigami who fights fallen spirits and guides pure spirits to Soul Society, Ichigo's abilities take a sudden upturn as he saps the girl's power and becomes a Shinigami himself. Thrown into a situation far larger than he expected, Ichigo's problems are further enhanced by Unification into the Multiverse. Faced with multiple threats from every direction, Ichigo, Rukia, Soul Society, and Karakura Town suddenly come into a brand new world, compunding the confusion of Ichigo's power-gain.