Lyza

Lyza the Annihilator, is a legendary white whistle who accomplished many great discoveries about the secrets of the Abyss. She is Ouzen's apprentice and Riko's mother. She took in an apprentice named Jiruo.

Ten years before the current storyline, Lyza took a dive into the Abyss and has not returned.

[Spoiler] However, a collection of some of her findings in the Abyss, along with a note to Riko, were found by the White Whistle Ouzen. [/Spoiler]