Fern

Fern is a young mage traveling with the elf sorceress Frieren, sharp-tongued and precociously competent, forever nagging her teacher to eat, sleep, and act her age despite being centuries old. Raised from childhood among adventurers, she carries herself with a brisk, no-nonsense practicality that masks how much she has already lost.

Kana Ichinose plays her exasperation as tenderness in disguise, the deadpan scolding never quite hiding real devotion. Fern gives the show its human clock, ticking against Frieren's near-immortal drift, and her insistence on discipline and study reads as a quiet, private way of grieving people she can't get back.