Imiko Toshite Suterareta Shoukanshi, Jitsu wa Sekai Saikyou

A mysterious figure who commands spirits beyond comprehension... a summoner. Born with a skill loathed by the nobility, Rybert grew up despised even by his own parents. No matter how hard he tried, his efforts were always ignored. The only person who ever believed in him was his younger sister, Azria. But when his sister became the victim of a bandit attack, his parents blamed it on him and cast him away. Consumed by despair, Rybert collapsed in the streets, where he was found and taken in by Sasha, a guild staff. No longer bound by his torment, his powers as a summoner started to awaken.