The story is set at the dawn of the industrial revolution, a period when feudal Japan was in turmoil. The ruling Shoguns abuse their power to dominate their oppressed subjects through beatings, imprisonment, rape, and murder. Determined to end the bloodshed, a group of samurai has banded together, aided by new weapons and technology, to stand up and fight. Ichimatsu, known as Samurai Gun, is one of these fighters. By day, he works incognito at a local tavern; in the evenings, he frequents brothels. However, during the night, he fights to bring justice to his world.