Senkaimon

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

Overview
Soul Society and the Human World are parallel worlds. The Senkaimon is the gate used to travel between the two worlds, and is the only official and safe way to enter and leave Soul Society. The Soul Society has only one permanent Senkaimon, which 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 only officially be opened by the members of the Kidō Corps. Upon opening the gate doors, white light emanates from the door and extends upward into the sky of Soul Society.

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

For high-level Shinigami, such as Captains and Lieutenants, a seal is automatically placed onto them whenever they pass through the Senkaimon from Soul Society to the Human World, limiting their strength to 20% of their maximum output. This is done to prevent their Reiryoku from causing undesirable ripples in the Human World, but they can request for the seals to be removed if the situation calls for it. Under critical situations, such as the battle against the Espada, the seal is not applied even when the Captains and Lieutenants pass through the Senkaimon.

While the Senkaimon is run by the Kidō Corps, some high ranking Noble Families have their own 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 inserting it into the spacial area one wants the Senkaimon to appear before turning the sword like a key. As the crease of the door appears and fully opens, another door beyond it opens, releasing the Jigokuchō. 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. This is much more dangerous to do, as souls who cannot pass through before the gate to Soul Society closes are trapped there forever. It is possible for those in the Seireitei to deactivate these mechanisms, allowing Shinigami or Humans to traverse the Dangai safely.

Variations

 * A device which converts kishi into Reishi.


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


 * A gate that a Royal Guard can open, sending someone directly to the human world from the Soul King Palace. The gate can also be opened to send this person back, but to do so requires syncing the arrival and departure times.