Everyone has the ultimate ideal of entering cities A, B, and C, where the world's most cutting-edge technology, the most gorgeous products, and the most complete services are available. But the conditions are extremely harsh, and there are very few people who enter without authorization through their own efforts... What do those people know? Any idea of an ideal city or the forefront of the world is all nonsense! It is a shackles that entangles people, a city that hides sin. It is said to be so beautiful to the outside world, an ideal city - a city of sin.