Tsuihou no Kenja, Sekai wo Shiru: Osananajimi Yuusha no Atsuryoku kara Nigete Jiyuu ni Natta Ore

The wizard Hal finally made up his mind to leave the party of his childhood friend and famed heroine Leticia, after putting up with her abuse for far too long. His new life as a free adventurer will lead to new encounters and a search for his "true self" that no one knows yet.
(Source: Kodansha, translated)