You play the role of Kou, a young boy who has just celebrated his 15th birthday. Years ago, your father disappeared while exploring the treasure-laden Monster Tower, a massive structure filled with a variety of dangers. Now, you are finally old enough to go to the Tower and find out what really happened to your father. Since many explorers have surely charted out the Tower beforehand, finding what you are looking for should be a snap, right? Not quite, because the Monster Tower changes its entire layout every time you visit, providing new challenges and areas to explore every time you enter. What doesn't change, however, is the number of monsters lurking around looking to end your quest. To help fight them, you can enlist some monsters of your own. Combined with the tons of treasure you'll find, you'll be well equipped to tackle the dangers of the Tower.