Kellen Lars is, by his own admission, the most unremarkable person on Earth — until his little sister vanishes before his eyes and he awakens in Oras, a world where Beastcallers channel elemental forces alongside animal companions called Mana Beasts. Oras is a place of magical storms, animal demi-gods, and warring tribal factions, and Kellen's only lead on his sister is to grow strong enough to search the entire continent. Bonded with a mana beast named Vex, he begins the long climb from helpless outsider to genuine power.

Kellen is defined by his ordinariness — and by how stubbornly he refuses to let it stop him. He is methodical rather than reckless, emotionally honest rather than brooding, and his relationship with Vex is the series' emotional heart. Reviewers consistently praise the genuine warmth of the beast-companion bond and Kellen's refusal to treat his underdog status as an excuse.

Two books chart Kellen and Vex's early progression — from surviving Oras's most hostile environments to climbing the Storm Totem, a colossal structure that serves as both dungeon and proving ground. The broader world grows darker as cultists emerge for the first time in a millennium, spreading chaos in service of a vengeance-driven crusade. The series blends Pokémon-adjacent beast-bonding with genuine progression fantasy stakes, building toward an eventual confrontation with forces far older than anything Kellen has yet faced.