Denreishinki

The is an electronic inter-dimensional communications device used by Shinigami while on an assignment in the Human World. The Denreishinki looks nearly identical to the cellphones found throughout the Human World, and comes in many different designs.

Overview
The Denreishinki is a device used by numerous Shinigami stationed in the Human World. It allows direct two-way communication between a Shinigami in the Human World and a person in Soul Society. Shinigami can receive orders via the device in text form, which they are alerted to by the device's distinctive beeping. The device contains a system similar to a radar or GPS tracking system for Hollow detection. Hollows located within a given area will be indicated in a mapping function of the device. It can detect nearby Shinigami and inform the user of whether they are geographically the closest to their target.

Other functions of the Denreishinki include recording of a Shinigami's bounty rewards for purifying Hollows. These logs can be accessed by connecting a larger handheld device to the Denreishinki. Rukia Kuchiki can access and print off the recorded history of the Hollow Grand Fisher using her Denreishinki. Its ringtone can be customized. For example, Ryūnosuke Yuki uses a recording of Shino humming as his ringtone.

After the war with the Quincy, Kisuke Urahara began working with Soul Society to introduce new technology which included a new model of the Denreishinki that mimics smartphones and allows for video chats.

Appearances in Other Media
In BLEACH, Rukia's Denreishinki takes the form of a palm-sized, lightbulb-shaped glass stone that glows with purple light and displays spiritual beings like Shinigami and Hollows on the top of the "screen" with a map of the surrounding area. The Denreishinki is powered by disc-shaped batteries, and the interior of the battery compartment is ornately decorated with a skull visage surrounded by a radially symmetrical arrangement of circles, puzzle piece-like squares, and short repeating lines.