The Prince's Apprenticeship
Kage pleads with Desha's brother Despa to make Bojji powerful enough to be king, and Despa takes Bojji on as an apprentice. After making his assessment, Despa is astounded by how little power Bojji actually has, but refuses to give up on training him.
Aired 26/11/2021EP 7 - The Prince's Apprenticeship

2021
Ranking of Kings
Unable to hear, speak, or wield a sword, Prince Bojji doesn’t seem like a typical heir to the throne—and his kingdom agrees. But his fateful encounter with Kage, a shadow on the ground, gives him his first true friend. The two set off on a grand adventure and, together, form a bond that can overcome any obstacle...even being king.
(Source: Funimation)