If the gacha is the problem then... It's random so I can't help xD
If it's the quest, find a crystal tail in the HUB, in the morning or afternoon (Do not appear nightime), and click on it Then after that, check the Adventure guild, same, a crystal tail appear, click on it Then go to your room, the last crystal tail is here, click on it.
After that, it will be easier, cause you will see a "?" quest in your mini map
