White Whistle

White Whistles are second grade artifacts that can only be used by their original owner. They are made from Life Reverberating Stones and given further shape by the user's own modifications to the stone, making each and every White Whistle unique. White Whistles are able to activate dormant relics.

The White Whistle is a signature characteristic for the few divers that are allowed to dive past the fifth layer of The Abyss. Currently there are only a handful of recognized White Whistle users, although it's unknown whether or not all of them are still alive.

Life Reverberating Stone
It is revealed by Bondrewd that White Whistles are made out of Life Reverberating Stones. Life Reverberating Stones are white stones created by the death of a human. If a person dies and possesses deep loyalty or love toward another person, they can potentially turn into a Life Reverberating Stone. Each Life Reverberating Stone possesses a life pattern unique to the person sacrificed for the stone; the pattern is only compatible with whomever the deceased perished for. Hence, the White Whistle can only be used by the individual it was intended for.

It is possible that some form of consciousness of the sacrificed person remains within the Life Reverberating Stone; when Riko, Nanachi, and Reg find Riko's stolen White Whistle being altered by a Narahate, Riko stops Reg from taking it back, sensing that Prushka "did not hate it". Prushka was also seemingly able to communicate with Riko through the Life Reverberating Stone, but only said "Call me". It can be assumed she was telling Riko to activate the stone's ability.

Life Reverberating Stones have the strength to pull out the true purposes hidden within certain artifacts; it reacts into another relic, similar to the way the tone of White Whistles do.

Thus far, the only individuals known to have died for the creation of a Life Reverberating Stone are: Currently, it is unknown who died for the creations of the Life Reverberating Stones used to create the whistles of Ozen the Immovable, Lyza the Annihilator, Srajo the Obscure, and Wakuna the Chosen.
 * Bondrewd, whose stone was used for his own White Whistle.
 * Prushka, whose stone was used for Riko's White Whistle.

White Whistle Owners
There are only a few known people who own or have owned White Whistles:
 * "The Lord of Annihilation", Lyza the Annihilator
 * "The Immovable Sovereign", Ozen the Immovable
 * "The Lord of Dawn", Bondrewd the Novel
 * "The Lord of Mystery", Srajo the Obscure
 * "The Lord of Guidance", Wakuna the Chosen
 * Riko

Trivia

 * Currently, Riko is the only person known to be in possession of more than one White Whistle; her mother's was passed down to her after it was brought up to the surface by Habolg, and Riko's own White Whistle which she obtained at the end of the Lord of Dawn Arc following Prushka's demise and subsequent transformation into a Life Reverberation Stone.
 * A white whistle recovered after its owner's death or Last Dive is traditionally given to their surviving family or descendants. If it's declined or the delver has no living relatives, the whistle becomes property of the Delver's Guild and is kept at their headquarters in Orth.