Ozen

Ozen is the White Whistle who rules the Fifth Layer, a towering veteran cave raider nicknamed the Immovable Capital. When Riko and Reg arrive seeking her guidance, she meets them with blunt indifference, cryptic tests, and a taste for cruelty dressed as instruction — offering knowledge only to those who can survive earning it.

She is a wall of contradictions: monstrous strength paired with childlike pettiness, wisdom delivered like a threat. Sayaka Ohara plays her with a low, unhurried voice that makes every offhand remark sound dangerous, so you never quite know if Ozen is testing the heroes or simply amusing herself at their expense.