Illusory Urahara, located in the vicinity of a shrine in Harajuku, is the only purely optional Idolasphere in the game. Rather than a dungeon, it is an arena where the player can earn rewards by taking part in series of battles. Arena battles come in three difficulties; Beginner, Intermediate, and Advanced. One round in the arena consists of five battles against Mirages without a break. If the player wins, the option is given to continue with encore performances against a second and third wave of enemies. The arena also offers a daily challenge battle; a special fight that can be challenged once per day.
Additional rules of the arena include:
- The player cannot swap active party members out during arena battles.
- Losing in the arena is the same as losing in a standard battle and will result in a Game Over.