Statue

Modern sound rings operate using a system called Soul Imprints. A person can collect Soul Imprints from friends and those they wish to communicate with through something known as Soul Imprint Cards—another invention of Robin's. This allows for effortless mental communication at any time and from any place, as long as both individuals remain on the same planet. However, if the other party leaves the planet, messages can still be sent but will remain undelivered until both are once again on the same celestial body.

Severing a communication channel or being unable to select a Soul Imprint for contact is theoretically possible in only one scenario—if the imprint is no longer viable, if it has ceased to exist. And when someone's Soul Imprint disappears… it signifies only one thing: death.