Underground people who exhale toxic gas appear in Tokyo's S-Ward, which is dealing with construction noise from urban development projects. Everyone panic, but it turns out that five middle-aged guys are unaffected by the poisonous gas.

Strange creatures suddenly appear in a peaceful town. Exhaling a poisonous gas that people find irresistible, the undergrounders attack. When people begin to give up fighting, 5 men who are immune to the poisonous gas appear. They are under appreciated by their families and co-workers, but these 5 men stand up to protect their families and the town.