Mirai Arc Complete
Completed all of Mirai's missions in Shinobi Girl's Heart.
Each character has 5 missions to complete. They're not necessarily related to the story...more of a fun side-quest style thing.
They are rather easy, and provide insight to the character's backstory. You shouldn't have any trouble with these, and should probably do them first to make the story easier (levels carry over).
When you complete it, you'll unlock a new piece of Art to purchase from the store.