Senkaimon

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

Overview
The Soul Society and the World of the Living are parallel worlds. The Senkaimon is the gate used to travel between the two worlds. The Senkaimon is in fact the only official and safe way to enter and leave Soul Society. The Soul Society has only one permanent Senkaimon, it takes the form of a giant gate situated within a large courtyard atop a large tower. Travel through the Senkaimon is heavily regulated and can officially only be opened by the members of the Kidō Corps. Upon opening the gate doors there is nothing but white light the emanates from the door, this light extends upward into the sky of the Soul Society.

A black winged insect, the Jigokuchō that only Shinigami are permitted to carry, is needed to pass through it.

While the Senkaimon is run by the Kidō Corps, some high ranking Noble Families have been shown to have private Senkaimon.

Usage
Upon arriving and leaving from the Human World the Senkaimon can appear almost anywhere. When it appears in this fashion the Senkaimon takes the form of a traditional Japanese waiting room entered through a Shōji. It can be opened by using a Zanpakutō as a key. The method requires simply placing the Zanpakutō in front of the user and then inserting it into the spacial area one wants the Senkaimon to appear and turning the sword like a key. The crease of the door then appears and fully opens followed by the opening of another door beyond that releases the Jigaokuchō.

Variations

 * Spirit particle conversion machine. A device to convert kishi into Reishi. Ichigo Kurosaki and his friends go to the Soul Society.


 * A variation of Senkaimon where four giant pillars are placed at four corners to replace the space within it with another space.

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.