Occhan Boukensha no Senya Ichiya

"Occhan" is a humble middle-aged adventurer who makes a living accepting jobs from a guild in a certain town. But his true form is a "Shape-Shifter," a dungeon monster. He used his transformation abilities to live a carefree second life in a peaceful human town. Just as he has acquired the life he wanted, he lets his kindhearted nature gets the better of him and he finds himself poking his nose into all kinds of troublesome business. But every time, he uses his transformation skills and his experience in the "monster world" to resolve one incident after another. Source: Hobby Japan