When Ichigo is first told that Soul Society is only a stone�s throw away he went rushing to it. He was only disappointed as he discovered that the way was blocked by a wall that seemed to fall from the sky. These walls are composed of a material known as death stone. This material can drain all the spiritual energy from a person if too close. These walls surround all of Sereitei and are only able to be bypassed via four gates at each direction. Each Gate is guarded by a Guardian (although Ichigo's team managed to break the barrier using Kuukaku's cannon).
Anyways, even if you manage to defeat the Gate Guardian there is still the task of opening the gate. The gates are incredibly heavy and require immense strength usually possessed by the guardian themselves. Basically the only avenues open to enter the gate are to befriend the guardian, hypnotize the guardian, or have immense strength.
