Senkaimon

The is the dimensional gateway which Shinigami use to enter and leave Soul Society by unlocking it.

Overview
When guided by a Jigokuchō, the Senkaimon takes the form of a waiting room entered through a sliding door. This was first seen used by Renji Abarai when he opens the Senkaimon by Byakuya Kuchiki's command. He opened the Senkaimon for Byakuya, himself and Rukia Kuchiki. The Senkaimon is used for Soul Society citizens (Shinigami, Souls, Zanpakutō Spirits, etc.) Humans can also use such a gate through the use of, which convert solid matter into spirit particles.

The is a variant on this gate by using four linked points to create one spiritual unit of area radius that swaps something that it encircles with something else in Soul Society, as is done to Karakura Town to prevent Sōsuke Aizen from destroying it.

Intruders can pass through the Senkaimon in the same manner. While this method uses the same gate, the lack of a Jigokuchō forces intruders to pass through the, a bordering dimension between the Human World and Soul Society (not to be confused with Hueco Mundo). This is much more dangerous to do, as souls that cannot pass through before the gate to Soul Society closes are trapped there forever. It is possible for Seireitei to deactivate these mechanisms, allowing Shinigami or Humans to traverse the Dangai safely. While the Senkaimon is run by the Kidō Corps, some high ranking Noble Families have been shown to have private Senkaimon.