In a different world that’s similar to modern-day Japan, ‘magic’ exists alongside science and technology. It may seem like a peaceful world, but there are many irregular happenings which commonly occur out of sight. They are the work of the ‘handymen’, individuals who work for the ‘Underground Society’, doing any job so long as it doesn’t break the law.

Seigi is a young man who is true to his name: a strong-willed believer of justice. While he is part of a special police force, he currently disguises himself as a handyman. One day, he was assigned the job of protecting a mysterious girl Ruru who lost her memories. Their accidental meeting would set a small gear in motion, which would gradually roll in those closest to him.