King Baal's Legatee

For thousand of years, Earth has gone through many evolutions that led us here, 2150 the present day. Until one day, 71 Dungeons appeared around the World. This Dungeons was called "The King Solomon's Demons" but wasn't it supposed to be 72? Why is there only 71 that came out? Follow our young protagonist as he discovered the last dungeon underneath the basement of his house.