Masayuki

Masayuki is an Otherworlder of Russian and Japanese descent. Due to the effects of his Unique Skill "Chosen One," he was deemed a Hero against his will. During Rimuru City's Capital Opening Festival he got acquainted with Demon Lord Rimuru and later became his subordinate, taking the role of Tempest's spokesperson for adventurers and advisor for the Labyrinth.

(Source: That Time I got Reincarnated as a Slime fandom)