Apparently the message at the end of the events wasn't clear enough, my bad. Maybe I should've mentioned that in the update notes instead to avoid confusion. Dea can't be found yet. She'll be added later. The dialog was only meant to implement Mai's backstory and prepare for Dea to appear later, it was not supposed to be a hidden clue to make you search through the entire game. ^^" My bad.
So after learning Mai's story, I ran around everywhere to find her unfortunate sister and reunite them again in happiness while she doesn't even exist yet?
*sigh* Oh well, I can't help it, I will have to wait for you complete the story in order for me to bring them happiness like I do to everyone. :-)
Thank you for continuing Ryen's story, I enjoy it very much. ^_^