Kabe-yaku nado Fuyou to Tsuihou Sareta S-kyuu Boukensha, "Dorei Kaihou" Skill wo Kushi Shite Shijou Saikyou no Kunizukuri

Alex, a holy knight, is suddenly expelled from his adventurers' party. He tries to live a comfortable life by accepting a quest to cultivate a remote area, but suddenly he is given the extra skill "Slave Release"...? Summon beautiful girl slaves and cultivate a demon territory overrun with demons! A slow life of harem in a fantasy world is about to begin!