A world where magic has declined and can no longer be used without the aid of magical tools. Philz, the second son of a duke, has had fragmented memories of his past life in dreams since he was a child. As a result, he is mentally precocious, and is fed up with the poor relationship between his father's first wife and Philz's mother, the second wife. To relieve stress, he secretly wants to do detailed crafts such as puzzles and plastic models, which were his hobbies, and he becomes secretly dissatisfied. So he begins his activities, hiding his identity with a transformation set. He is very independent, and quickly obtains the status of an adventurer, secretly developing his own magical tools to add convenience to his daily life.