A middle-aged adventurer, "Uncle," who lives in a certain city at the request of a guild. However, the true identity is actually the dungeon monster "Shape Shifter". He took advantage of his feat's transformation ability and decided to live comfortably in a peaceful human city for his second life. He got to know Alisa, the receptionist of the guild, and was able to get the life he wanted for a while. However, each time, the uncle makes full use of his specialty transformation and the experience and wisdom cultivated in the "monster industry" to lead the cases to resolution one after another. A humorous and exciting "Uncle"'s great success ... The fantasy adventure tan full of individuality has finally begun!