X Day (or 10 Day) is a monthly event held on the tenth of every month. Each month has a different small event happen along with common things that come with every single month.
Applies each month
These gift tickets are used to get exclusive items. List here. These are picked up from a Puku npc holding a balloon in one of the 5 towns (Gatara, Orphea, Glen, Julet and Azlan). The location changes each month. You can get 1 ticket from them each month per character.
This month's location
Wind Town Azlan (F5)
Free Boss Card in the Magic Labyrinth
Talk to the Puku with the balloon and you can get a boss card that can be used in the magic labyrinth. These will expire after 2 weeks.
Nyan coin Sale
Nyan coins are cheaper, being able to buy 7 coins for 50 mini medals.
Only available for people who cleared V3