Yuna traveled into the fantasy world. The gods of this world gave her a powerful set of equipment so that she could defeat many fierce monsters. However, she had limited health points and stamina, and she could not kill a large number of monsters.

Adventurer's guild would release monster crusade missions, such as black python and wild wolf. Completing the -th mission would consume Yuna  health points and  stamina, and then she would get  gold coins.

In the beginning, Yuna had health points and stamina. When her health points were dropped to less than or equal to , she would die. However, when her stamina was dropped to less than , she would not give up, and then the overdrawn stamina would be reduced from health points. For example, her health points would be reduced by , when her stamina dropped to , and then her stamina would be reset to . If her health points can not afford the overdrawn stamina, she would also die.