The true name of Ichigo Kurosaki's Zanpakuto, or Soul Reaper's sword, is "Zangetsu." Zangetsu serves as the embodiment of Ichigo's powers and takes the form of a large, black katana. Zangetsu is a crucial aspect of Ichigo's abilities and plays a significant role throughout the "Bleach" series.

Zangetsu has its own distinct personality and often provides guidance and training to Ichigo. In its initial manifestation, Zangetsu takes the form of an older man with white hair, known as "Old Man Zangetsu." However, as the story progresses, it is revealed that Old Man Zangetsu is not the true Zanpakuto spirit but a manifestation of Ichigo's Quincy powers.

Later in the series, the true form of Ichigo's Zanpakuto is revealed to be a much younger and more powerful entity named "Zangetsu." This version of Zangetsu represents Ichigo's true Shinigami powers and guides him in honing his abilities. The true Zangetsu has a different appearance, with a black cloak and a chain wrapped around his arm.

Zangetsu is an integral part of Ichigo's journey as a Soul Reaper and plays a pivotal role in his battles and character development throughout the "Bleach" series.