Gems are the premium currency in this game. They can be earned in-game by:

  • Clearing a quest for the first time
  • Stepping on every platform of the map (you do not need to explore them)
  • Completing Missions
  • Participating in special events

Other than that, the only method of acquisition is to buy them with real-life money. The prices are in yen (円 or ¥), and you can convert yen prices here. Gems are used for:

  • Summoning weapons from the gacha
  • Fully restoring AP
  • Restoring party HP when defeated in combat - some quests do not allow this usage, or restrict it to only a certain number of occurrences