Custom, a swordsman from a small village, is on a journey when he comes across a carriage being attacked. He defeats the attackers, rescuing the lovely maiden Kumiko. Kumiko was on her way to Toushin Toshi (Combat God City) to search for her father. She suspects her father is in the Combat God Mansion, residence of the annual combat tournament's champion. In order to get in, she needs to partner up with someone who can win the tournament that year, and Custom agrees that she can be his partner. They head to Combat God City to enter the tournament.
Although victory in each round of the tournament earns one gold, special medicine, and other wonderful prizes, perhaps the most interesting prize is the opponent's partner. Each participant is required to have a beautiful female partner, and if the participant loses in combat, the victor gets his or her partner to do with as he/she pleases for one night. Female warriors in the tournament can choose to act as their own partner, as do the ninja Yayoi and swordswoman Morris.
This monster-filled underground maze is located on the outskirts of Combat God City. One of the requirements to participate in the tournament is the retrieval of a Hero Crest from here. While the Hero Crests are on the first level of the labyrinth, there are several more floors and surprises waiting deeper inside.