Aside from her original role in Final Fantasy VII, Yuffie has made several other cameo appearances in the game franchise. In the Dirge of Cerberus, she helped Vincent and aided the WRO in their fight against Deepground. She also encountered Zack in Crisis Core and enlisted him to help her find treasures in several of the game’s side missions.
I can say one thing, she’s pretty daring to be wearing Yuffie’s clothes during Winter Comiket. Thanks again to Somiya for sending this in!