A fanmade character based off of Rumia from Touhou.
It has been speculated that the ribbon on Rumia's head acts as a seal on her true powers.
In EX form, she commonly wields a large sword and freely manipulates darkness. She is also sometimes depicted as an adult and/or with wings in this form. It is also not uncommon to see her ribbon floating above her head in a similar fashion to a halo.