Jiruo

ジルオ

Jiruo serves as an instructor at the Beruchoro Orphanage. Holding the rank of Moon/Purple Whistle, he is positioned one tier below Black Whistles, a status that qualifies him to train future cave-raiders. His mentor was the legendary White Whistle, Lyza The Annihilator, and he has known Riko since she was a toddler.
Jiruo is a capable and strict instructor who never permits the eager Red Whistle Riko to exceed the depth limits set by her experience. When the children break rules or act unruly, Jiruo knocks them on the head to correct their behavior. Despite his strict role, he cares for the orphanage children and worries about their safety, doing his best to shield them from the horrors of the Abyss.