Sono Monban, Saikyou Nitsuki

Sieg is an adventurer with an incredible defensive power, and he always uses himself to attract the monsters' attention to assist his teammates. However, the party leader just focused on offense without realizing Sieg's intention, so he kicked him out. After Sieg left, the team repeatedly failed multiple quests ... At the same time, Sieg took the position of gatekeeper at the Royal Capital. Thanks to his defensive power, he was quickly promoted to division captain. His subordinates included a carefree big-breasted Swordswoman, a perverse freakish girl, and an Archer with an erratic temperament. He and the girls started slowly gaining the trust of people around them! (Source: Mangamonster.net)