This gateway is one of the ways for those who need to to easily reach the world of man. At most points in the day it is open allowing for free travel among the worlds for those who need it, but should something happen Giobe may close it for the safety of either the Soul Society or the Earth. So far Giobe has only had to seal the gate twice since he was captain, once to keep a bount in and once to keep hollows out. Once the gate has been closed nothing can open it for a full seventy two hours as a security restriction since the threat should be destroyed by then. If the gate has to be opened within that short time range six captains besides Giobe must be present and whole heartedly agree that it must be open, if one doesn't the gate will sense it and stay closed. At certain points in time it may become necessary for the lieutenant or the other seated members to guard the gate if it is ruled that closing it is mandatory but that protection is indeed needed, until then though it remains as a node connecting two different planes of existence and allowing reapers to do what they need to in the real world and find their way safely home.
