“Once Upon a Time” fans received some happy news Tuesday when it was revealed that actress Jamie Chung would be reprising her role as fierce warrior Mulan in Season 5. But where has she been all this time?

E! Online broke the news, and series co-creator Adam Horowitz confirmed the casting on his Twitter:

But unfortunately other than that, details about Mulan’s return are being kept under wraps. Although the Season 5 synopsis and upcoming episode titles have been released, nothing hints at how (or where) Mulan will reappear, or which characters she’ll be interacting with. The only thing Horowitz clarified for his Twitter followers is that she'll be in more than one episode, and that they are planning on including her in Season 5A and Season 5B.

Season 3 of “Once Upon a Time” was the last time that viewers saw the warrior princess. After initially getting tangled up with Emma (Jennifer Morrison) and Mary Margaret (Ginnifer Goodwin) in the Enchanted Forest, Mulan and Aurora (Sarah Bolger) led a quest to save the soul of Aurora’s one true love, Prince Phillip (Julian Morris). The twist is that while Mulan helped Aurora, she hid her true feelings that she was in love with the sleeping beauty. The two ultimately rescued Phillip, and then once again found themselves in some trouble thanks to Neal (Michael Raymond-James). Neal revealed that he was trying to rescue Emma and his son, Henry (Jared S. Gilmore), who was stuck in Neverland. The group promised to help, and they kept their word. Neal was able to follow a shadow to Neverland, leaving Mulan, Prince Phillip and Aurora in the Enchanted Forest with some new friends, Robin Hood (Sean Maguire) and his Merry Men.

Robin Hood was impressed with Mulan’s skills and asked if she would join the Merry Men. Mulan was intrigued but left to speak to Aurora first. It seemed as if Mulan was going to confess her true feelings to her friend, but then Aurora revealed that she was pregnant with Prince Phillip’s child. The news ultimately led Mulan to accept Robin Hood’s offer to join his group … and “Once Upon a Time” fans haven’t seen her since!

Robin Hood and his Merry Men end up in Storybrooke after the second dark curse, and so does Aurora … but no one has seen Mulan.

Mulan is not the only character returning to the show this season. Lancelot (Sinqua Walls) is also being reintroduced as Emma heads to Camelot in the Season 5 premiere. Ruby (Meghan Ory) is also reappearing after being missing in action throughout Season 4.

“Once Upon a Time” Season 5 premiers on ABC on Sunday, Sept. 27, at 8 p.m. ET. What do you think happened to Mulan? Tweet your thoughts to @AmandaTVScoop.