Each difficulty is unlocked by meeting the following conditions.
Normal | Normal quests are unlocked as cleared by progressing through and clearing portions of the main story, except for "1-1 Around the Royal Capital" which is unlocked as not cleared. |
Hard | Once a chapter of the main story has been cleared, a Hard quest for that chapter will be unlocked. Further quests will be unlocked as each Hard quest is cleared. |
Very Hard | Clearing all Hard quests for a chapter unlocks a Very Hard quest for that chapter. Further quests will be unlocked as each Very Hard quest is cleared. |